I’ve got a workaround for this issue. It involves digging into the rails console (backup first!):
In the server
cd /var/discourse
./launcher enter app
rails c
Convert the user
Then convert the user so that they are no longer staged:
Email address of the staged user to be converted
User.find_by_email("=EMAIL=").update(staged: false)
Upload their picture
Just as you would any other user
Convert them back to staged
Probably not necessary unless you really want them to stay ‘staged’
User.find_by_email("=EMAIL=").update(staged: true)
Done! Don’t forget to exit the console.
I haven’t had any issues with this (yet), but make no promises!