@Travis So the conclusion is "No luck either though.".
Actually it's my first time when I had update elementary os trouble. I think that elementary os creators should read elementaryos.stackexchange.com from time to time ;). Faltpak in their opinion is "the future for our AppCenter ecosystem".So I try to send them this link of troubles. Not so easy I'm ...
I have the same situation since yesterday morning. So far I haven't any solution but I found this:
According to Hector R on this issue on GitLab
flatpak install org.freedesktop.Platform/x86_64/19.08
flatpak uninstall --unused
NOTE: in the latest step maybe the system update some packages and ...
what I recommend you is to try to do this using command lines. Open your terminal application and execute
! without sudo, otherwise you will receive an error message. Another option that works for me in a bit complicated situations is sudo flatpak repair.