The problem is that navigation and other functions are disabled:
- Left/Right keys don't work
 - PgUp/PgDn don't work
 - the left/right arrows in the toolbar are greyed out.
 - Del doesn't bring up the delete dialog (it works fine in the Browser view)
 - F2 doesn't rename (it also works fine in the Browser view)
 
Version 0.93 64bits (Jan 31 2019)
(I dislike the HEIC format, but that's how my friend's iPhone shoots, and I have to put up with it)