I was poking around some more and found that something similar to this has occurred a few times with no real resolution, that I can tell.
This thread had the error but seemed to get around it by trying the table again immediately (which didn't work for me):
AGOL: Attribute Populates in Table, Doesn't Show in Pop-Up When Selected as Parameter
This thread saw the table initially but then it was lost when trying to access it again:
Accessing data failed (Show Table)
This recent thread is having the issue after using Survey123. Though it seems to have a similar issue to what I'm seeing:
Accessing data failed
The most similar case is this thread:
"Accessing data failed" Error in ArcGIS Online
Still, the one thing they all have in common is the error message and no resolution (or any replies)