Did you find what the problem was in the child theme? I am having the EXACT same issue, with the ghost 1969 group creation and everything. In group creation, everything seems to work just fine until the upload avatar page, where the form doesn’t show up.
The only files I have customized are the header and footer templates, and they should have all the important WordPress/Buddypress snippets necessary. Is there something in particular I should be looking for?