There is no doubt an unchecked or checked box lurking here: Two square images (identical) on a letter size sheet w/ample margins. If I try to rotate either, - or+ 90, QU seems to have its own idea....180...or? Same problem with Floating Text.
I can't see what your problem is here, all works as I would expect following normal mathematical conventions for positive & negative rotation. In the page editor, the text in the menu item makes it clear what will happen and works as it says. Same with floating text, eg. entering 270 deg gives the same result as -90 deg - all logical.
Another problem: I created a templated & saved layout. When I "run" the layout & click thumbnail(s) "+", (2 up on a letter sheet) - All's well. BUT if I click a "-" to replace an image, the whole works is deleted - back to an empty letter sheet - no layout, no images.
I think the problem here is that you have both images selected on the page preview (blue line around images); they should not all be selected if you wish to remove one image. Right mouse click and de-select all. When using a template, use this technique to clear the queue and you will be asked if the template should remain in use.
Terry