Primefaces graphicImage not refreshing with ajax

Question

Using Primefaces 6.0 with Glassfish Server 4.0 and JSF2.2 I want to be able to add and remove multiple images using p:fileUpload. Add is working fine but when I try to remove the image using commandButton with ajax, the logic works fine in the backing bean. Checked it using debugger. But as far as the page is concerned, graphicImage are not updating with the latest images.
Relevant Code for my jsf page as follows:

                <h:form id="tempForm" enctype="multipart/form-data">

                <h:panelGroup id="graphicImageCustomerPicturePanel" >
                    <div class="card">
                        <p:panelGrid columns="2" columnClasses="ui-grid-col-6,ui-grid-col-6" 
                                     layout="grid" styleClass="ui-panelgrid-blank form-group" 
                                     style="border:0px none; background-color:transparent;">

                            <c:forEach var="entry" items="#{tempBean.hm2}">
                                <h:panelGroup >
                                    <!-- Right colum -->

                                    <p:commandLink>

                                        <p:graphicImage style="height: 280px; width: 280px; margin-right: 10px;" title="#{entry.value.name}"
                                                        value="#{entry.value}" stream="false" cache="false"/>

                                        <p:ajax event="click" listener="#{tempBean.handlePictureSelect(entry.value.name)}" process="@this" 
                                                update="dlg"  />
                                    </p:commandLink>

                                    <p:commandButton value="Remove" ajax="true" actionListener="#{tempBean.removePicture(entry.key)}"  
                                                     update="graphicImageCustomerPicturePanel" style="width: 280px"/>
                                </h:panelGroup>
                            </c:forEach>

                        </p:panelGrid>

                        <p:fileUpload auto="true" mode="advanced" update="graphicImageCustomerPicturePanel" 
                                      fileUploadListener="#{tempBean.handleFileUploadCustomerPicture}" required="false"
                                      requiredMessage="File Should not be empty!"
                                      id="pictureUploadCustomerPicture" value="#{tempBean.uploadedFileCustomerPicture}"  > 

                        </p:fileUpload>
                        <p:commandButton value="Save Pictures" action="#{tempBean.savePictures('save')}" ajax="false"> 
                            <f:param name="reportTitle" value="Manage Customers" />
                        </p:commandButton>

                        <p:commandButton value="Update Pictures" action="#{tempBean.savePictures('update')}" ajax="false"> 
                            <f:param name="reportTitle" value="Manage Customers" />
                        </p:commandButton>
                    </div>
                </h:panelGroup>
            </h:form>

Managed Bean code is as follows:

private LinkedHashMap<String, InputStream> hm1, prevHm1;
private LinkedHashMap<String, DefaultStreamedContent> hm2;

public void removePicture(String filename) {
    hm1.remove(filename);
    hm2.remove(filename);

    try {

        LinkedHashMap<String, DefaultStreamedContent> tempHm2 = new LinkedHashMap<>();
        Iterator<String> it = hm1.keySet().iterator();
        while(it.hasNext()) {
            String key = it.next();

            InputStream tempIs = hm1.get(key);
            ArrayList a = cloneInputStreamAndDefaultStreamedContent(tempIs);

            if (a != null && a.size() == 2) {
                InputStream is = (InputStream) a.get(0);
                DefaultStreamedContent dsc = (DefaultStreamedContent) a.get(1);
                dsc.setName(key);

                tempHm2.put(key, dsc);
                hm1.put(key, is);
            }
        }
        hm2 = new LinkedHashMap<>(tempHm2);            
    } 
    catch(IOException e) {}
}

public void handleFileUploadCustomerPicture(FileUploadEvent event) {
    try {
        final UploadedFile uploadedFile = event.getFile();
        String filename = uploadedFile.getFileName();

        Iterator<Map.Entry<String, InputStream>> it = hm1.entrySet().iterator();
        while (it.hasNext()) {
            Map.Entry<String, InputStream> et = it.next();

            String key = et.getKey();

            ArrayList a = cloneInputStreamAndDefaultStreamedContent(et.getValue());

            if (a != null && a.size() == 2) {
                InputStream is = (InputStream) a.get(0);
                DefaultStreamedContent dsc = (DefaultStreamedContent) a.get(1);
                dsc.setName(key);

                et.setValue(is);

                hm2.put(key, dsc);
            }

        }

        ArrayList a = cloneInputStreamAndDefaultStreamedContent(uploadedFile.getInputstream());
        if (a != null && a.size() == 2) {
            InputStream is = (InputStream) a.get(0);
            DefaultStreamedContent dsc = (DefaultStreamedContent) a.get(1);

            if (hm1.containsKey(filename)) {
                String fn = filename.substring(0, filename.lastIndexOf("."));
                String ext = filename.substring(filename.lastIndexOf("."));
                fn = getNewFilename(fn, ext);
                filename = fn;
            }
            dsc.setName(filename);

            hm1.put(filename, is);
            hm2.put(filename, dsc);
        }
    } catch (IOException e) {
        Cm.setErrorMessage("Error: Owner Customer Picture not uploaded. Please try again later!");
    }
}

public byte[] getByteArray(InputStream input) throws IOException {
    ByteArrayOutputStream baos = new ByteArrayOutputStream();

    byte[] buffer = new byte[8192];
    int len;
    while ((len = input.read(buffer)) > -1) {
        baos.write(buffer, 0, len);
    }
    baos.flush();
    return baos.toByteArray();
}

public ArrayList cloneInputStreamAndDefaultStreamedContent(InputStream pis) throws IOException {
    ArrayList a = new ArrayList();

    InputStream is = null;
    DefaultStreamedContent dsc = null;
    byte[] b = getByteArray(pis);
    is = new ByteArrayInputStream(b);
    pis = new ByteArrayInputStream(b);

    if (pis != null) {
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        byte[] buffer = new byte[8192];
        int bytesRead;
        while ((bytesRead = pis.read(buffer)) != -1) {
            bos.write(buffer, 0, bytesRead);
        }

        dsc = new DefaultStreamedContent(new ByteArrayInputStream(bos.toByteArray()), "image/png");
    }

    a.add(is);
    a.add(dsc);

    return a;
}