We are using Portal and not AGOL. I have numerous surveys that have an image question with a multiline appearance. Users are on the web flavor of Survey123 - they need to be able to attach up to several 10's of photos to a survey. These are photos sitting on a file folder. Therefore, to make things easier for the user, he/she will select numerous photo from the pick images dialog. This has worked well - see attached photo

Now, and all of a sudden, this functionality is not working in Survey123 web - the pick image dialog only allows users to select one - and only one - photo.
Because we have so many surveys in the field, it is difficult to determine which ones work and which one's don't (some do and some don't - even with identical question type configurations).
So this is very frustrating and we're getting complaints from our users that the "select multiple photos" is no longer working. It seems to have occurred spontaneously - which is even more frustrating.
My question is: How can I ensure that the select multiple dialog works for our Survey123 users?
Setting Appearance to "multiline" no longer seems to "just work", and - most annoyingly - appears to have ceased working spontaneously.
Any guidance or experience with these conditions would be greatly appreciated.