I am facing a similar problem.
Not able to open whatsapp folder in file manager ,cannot delete or rename it either, cannot send and receive images and videos on whatsapp, cannot set status and see status , pretty much cannot do anything besides sending and receiving text msgs.
While sending an image error that I get is .. the file you picked is not an image
While downloading error is ... cannot download .
This is driving me crazy.
I tried cleaning cache, uninstall and reinstall whatsapp, go to safe mode and delete whatsapp folder, connected phone to PC and tried deleting whatsapp folder from there .. in normal and safe mode , but nothing at all helped and WAtsap folder was never deleted.
The problem arrived after I inserted a SD card in phone and by mistake selected , use as internal memory or something.... all my phone data was transferred to sd card , figured out it wasn't a wise choice for many reasons ,, migrated data back to phone memory.
I lost data from many apps in this process, but at least now those apps work fine , except for Whatsapp which is giving me a really hard time.