Alrighty this too borked too fix, there is literally no way for trickle themes to make it work.
The cut off thumbnails depend on the dimensions of the filename.jpg (or filename.png)
Let’s say you generate thumbnails in 240x360 and theme you are using is displaying it in 135x190
then the left side and the bottom will be cut off. This doesn’t really bother with thumbnails that have no borders but when you are using a trickle theme which is calculated on the last pixel or your thumbnails have a border frame it will cut off 2 pixels on top and the left.
THE ONLY WAY to have thumbnails displayed correctly is to generate them in the exact size as the theme wants to display them, which is another total NO-GO! It can’t be fixed otherwise. Not even the default themes work 100% correctly and on top of that they messed with the height alignment in Gallery View, it plummed 12 pixels closer to the bottom.
Whatever they call Adjustment Improvments in their release note is in fact a bug. It is unusuable and I suggest people complain so they’ll fix it.
There has been improvement in the backdrop display time and especially they got rid off the delay when you browse in Gallery View but the thumbnail issue is a complete mess, nobody asked for it, it takes away the freedom of how to create themes and many themes including my own look simply stupid.
Don’t upgrade and ask for a fix, because if this won’t be fixed the time where you can switch between themes is over because your generated thumbnails will be all messed up