Neural filters won't load at all and block Photoshop if opened image is 8bits grayscale
I posted the issue elsewhere, but it seems it got merged with another that has a different "correct" answer.
If you open a 8bits grayscale image and choose "Neural filters..." in the filters menu, Photoshop will spin a blue circle indefinitelt on the right panel and never open any filters.
Most menu items become unavailable and it's impossible to quit. You have to kill Photoshop in the Task Manager.
This is quite a serious bug.