I am having a similar issue.
I have just moved items from a colleague's ArcGIS Online content folder to my own. I kept all files in the same folders.
One moved file/folder is an active survey designed in Survey123 Connect. When I open this survey's files in Connect, I no longer have an xls form attached. AND the main survey icon is prompting me to refresh - but warns me "do I really want to download and overwrite?" - I'm worried about losing data and the survey content itself.
I have checked the folderID in My Survey Designs> iteminfo file on my computer, and it matches the folder ID enclosing the survey content in ArcGIS online.
I also no longer see the xls in My Survey Designs survey folder on my computer. Can I just upload the xls form into this folder again? And if so, what happens when I download and overwrite in Connect to refresh?
Lastly, I am using a new MacBook Air and understand that services will no longer be updated for Connect. Could this be part of the issue?