00437: Layer cannot access the associated data source
One or more data sources that are needed to completely draw a layer in your map or scene are not accessible. This may include:
A relationship class used for feature level masking
A broken data source, especially with cases where a relationship class has been deleted, may slow down drawing performance.
Solutions
Do one of the following:
Ensure you have connectivity with your associated data source. If not needed, remove the relate or disable feature level masking.
Remove the layer from your map or scene.