DisplayName is disappeared when Runtime is set

Question

I have a PowerPoint Add-in. There is a manifest file. It contains a tag

<DisplayName DefaultValue="Office App"/>

The taskpane has a header as expected:

Everything works fine until I add

<Runtimes>
    <Runtime resid="Defaults.Url" lifetime="long" />
</Runtimes>

With this tag, my taskpane does not contain the header anymore:

This tag is required, because Enable and Disable Add-in Commands programmatically possible only with shared runtime.

Manifest file checked, it does not contain errors.

Any idea why the label does not appear with shared runtime?