Okay, we're now on version 28.3 and another problem has been fixed. I can no longer make images disappear, but others still remain.
Disappearing images - fixed
Marquee select - not fixed
Moving multiple objects - not fixed
Snapping to object inside a block - not fixed
A few more updates and Blocks may be ready for release.

General usability has some workflow problems that I think deserve a look at.
The forced variant is awful, but if it's here to stay can we have it a little more consistent please? A few examples:
Skewing/Rotating does not transfer to the variant.
Adding Reveal Animations, Stretch Full Width and Sticky do not transfer.
The Fill Tool doesn't transfer...well, it does, just not properly. Try it.
Linear Transparency behaves in the same way as the Fill Tool.
Repeat On All Pages doesn't work at all.

There are probably a lot more, and all can be fixed by Stop Sharing With Variants, doing the edits, then sharing again. ORRRR, not force the variant in the first place!!!

Looking forward to Xara actually testing before releasing the next update.