I have a map of water data (mains, valves, meters, etc.) that just recently stopped showing layers. I've tried updating the feature layer. I've completely removed and re-uploaded the layer. I've even completely replaced the layer, map, and all files associated with the map. Nothing seems to make the layers show on explorer, even though they show in every other viewer (Pro, Web Map, Web App).
The only error I can see is when I open the legend in the explorer app. All the layers show "Invalid JSON".