I have a Feature layer created from Survey123 Connect that started returning this "undefined" error this AM.
We noticed it when field staff reported being unable to submit surveys via S123 Mobile App and when I investigated, I saw the error on attempting to open the FL overview page.
This happened last week and I was able to repair by clicking Rebuild Spatial Indexes in FL Settings page, but now I don't even get the option to open Settings (the Settings button is greyed out on FL Overview - see picture below)

Has anyone else come across this and is there a way to correct it? Not thrilled about the idea of losing all the data we've been collecting ...