mix-blend-mode: multiply - Firefox black bug

Question

I am building a ven diagram out of CSS and html. In firefox for some reason the mix-blend-mode is showing up completely black?

    .ven-element {
     width: 63%;
     padding-top: 63%;
     border-radius: 50%;
     text-transform: uppercase;
     font-weight: bold;
        mix-blend-mode: multiply;
     color: white;
     -webkit-box-shadow: inset 0px 0px 20px 1px rgba(0,0,0,0.22);
     -moz-box-shadow: inset 0px 0px 20px 1px rgba(0,0,0,0.22);
     box-shadow: inset 0px 0px 20px 1px rgba(0,0,0,0.22);
     position: absolute;
    }
    .ven-left {
     background: #82bf55;
     z-index: 3;
     left: 0;
     text-align: left;
     padding-left: 13px;
    }
    .ven-right {
     background-color: #2f9ad3;
     z-index: 4;
     right: 0;
     text-align: right;
     padding-right: 20px;
    }

    <div class="ven-wrapper">
   <div class="ven-element ven-left">
        <span>Left</span>
      </div>
   <div class="ven-element ven-right">
        <span>Right</span>
      </div>
 </div>

For some reason this shows up as 2 black circles in FireFox?

Answer 1

As discussed in the comments, the OP is using Firefox on OSX

Per CanIuse.com under "Known Issues" this is a bug

Bugzilla Reference