Thanks Philip. I couldn't find an existing bug for it and was surprised that I couldn't find anything searching geonet either. I'll submit a bug report right now.
ESRI Case: #02990215 Multiline Predictivetext appearance causes feature report generation to fail
I'll edit in the BUG# if it gets converted to a bug.
EDIT for posterity: This was confirmed as a bug (BUG-000146779), but using "predictivetext multiline" in the appearance column (instead of "multiline predictivetext") does work. While troubleshooting, we noticed that "multiline predictivetext" will work if it's present when the survey is first published, but not if it's changed after first publishing.
Just for the sake of continuity here...
This works fine, both in-app and in the feature report:
The portion of the feature report that prints out this response:
If I change it to multiline predictivetext and republish, the in-app behavior works as expected:
New records and existing records fail to generate with this error though:
And I start getting a syntax error when trying to upload an edited feature report (with appearance:multiline still set):