No, it affects all browsers - you'll see if you do a hard refresh that your themes do not work correctly.
Please double check your default theme is set correctly to a valid one.
It is set correctly to a valid one.
Can you check one and click "Update" just to make sure the setting is saved?
Done, nothing changed, though.
Ah, sorry, just realised I was looking at forumdisplay.php and the index works fine.
What has happened is that the upgrade script didn't set any forums using a custom theme back to the default.
Can you run a query via PHPMyAdmin:
UPDATE mybb_forums SET style='0';
It should set the forums back to use the default (after setting mybb_ to your table prefix).
I'll patch the upgrade script to revert the theme.
