I'm experiencing an unexpected behavior in Field Maps. Here's the situation:
I published a hosted feature layer from ArcGIS Pro to ArcGIS Online. I added the feature layer to a web map in the new map viewer and then configured the web map in the Field Maps app as I needed it. Up to this point, no issue. After inspecting the map in Field Maps, I noticed one of my fields was populated with data that I did not want. I opened my feature layer on AGOL, navigated to the 'Data' tab, switched to the 'Fields' view, and deleted the erroneous field. I re-created the field with the same name, so I'd have a nice <null> value in the whole column. I re-opened the Field Maps online app, added my new field to the smart form, and re-generated all my offline map areas to make sure my change would be recognized offline.
Here was the 'gotcha'. When I re-downloaded my map on my tablet, the symbology of my feature layer had been overwritten. This was a surprise, because the attribute that I deleted and re-added was not referenced by my symbology properties and I did not re-open the web map to change symbology after making the schema edit. I re-opened my map in the web viewer on AGOL and, sure enough, the symbology was not as I left it.
What's going on here? Is this a bug? I have a bad feeling it has something to do with a discrepancy between the new map viewer and the visualization tab of the feature layer (even though I didn't even open the visualization tab), but this is a wild guess.
By the way, I was able to fix the problem by overwriting the JSON with the appropriate symbology rendering properties. I'm assuming you could do it by overwriting the feature layer as well. Although I've figured out a fix, I'm mostly wondering if anybody else has experienced this issue or has any insight into why it happens?