One thing I did to fix this was just downgrade to a version before 5.0.8. as a temporary fix until the fix is resolved in the latest version.
Also another trick I have found is that when you’re creating the field in 5.0.8, make sure your image preview size is set to thumbnail and that the actual image you’re trying to set for that field is bigger than the thumbnail size. Don’t ask why that works too cause I have no idea.
Great tips. I thankfully have some breathing room to hold out for a patch for now BUT will downgrade if necessary. Very funny about the image being bigger than thumbnail because one of my images that wouldn’t assign WAS smaller that 150×150 and for the life of me I couldn’t figure out what about it was being discriminated about it… Turns out the dimensions were it, like you said.