We have this layer in a sde that is produced in enterprise portal. I recently have been converting from Web App Builder to Experience Builder and changing all maps from classic to Web map viewer. All of sudden one of our layers keep showing this error. and everything is greyed out on the right hand side. You can turn the layer on and off no issues there as to seeing it correctly on the map.
NOTE: The layer is in multiple maps and behaving the same in all the different maps. Also, in the sde no trouble editing this layer and seems to be no issues there.
Screenshots for reference.
data is inaccessible error
greyed out options even though the layer is selected.
I'm having the same problem. For me, I switched which map the widget was pointing to and reconfigured the widget, but now it doesn't display anything and gives the "data is inaccessible" with the red x inside a circle when entering the table configuration panel.
I fixed it by removing the tables broken tables from the Table widget and re-adding them.