Yesterday (2nd September) I was able to import/export PowerApps. Today (3rd September) both the Export and Import operation only get as far as "Creating your package" or "Importing your package" and then freeze.
I've tried with two different Apps on two different tenants with the same result, so looks like this could potentially be widespread...
Thanks all for raising this - can someone please send me a private message with a support incident you've raised? I'd like to check in on it's progress.
Learn how to create your own user groups today!
Check out the new Power Platform Community Connections gallery!
Congratulations, the new Super User Season 2 for 2021 has started!
Power Platform release plan for the 2021 release wave 2 describes all new features releasing from October 2021 through March 2022.