You can try clearing cache of the gallery app and see if that helps. Also report it here as a bug
Report the bug here .
It's still a beta build so bugs like this are expected. Post this in the beta build thread or you can even report it as a bug here....
Their partnership has ended, pretty sure it will get update in some time. https://twitter.com/FNATIC/status/1369593583767011328?s=09
The OnePlus 3/3t has reached EOL, it won't be receiving any updates whatsoever.