I may have jumped to a conclusion too soon. Although the iPad Air 2 was working yesterday afternoon, this morning it is in a deep funk where it can't even get to apple.com (or any other website) in Safari. In addition, the other iPads which were "working" yesterday may not have actually been working satisfactorily. Staying in the app for any significant length of time usually results in "This webpage was reloaded because a problem occurred." on the iPad Air running iPadOS v12.5.5. The iPad 6th Generation either hangs or reloads given enough time.