This is a long time issue with Image Props inside of Plants. See:
I should probably file a proper bug about it because despite what was said in that thread clearly nothing's happened about it.
Interestingly if you Group the Image Prop inside the Plant then the settings work but the consequence of this is that you can't scale the Image Prop afterwards using the Plant settings so not that useful a trick...
Tom W.'s post in Cannot turn off image prop crossed panes and auto rotation was marked as the answer