Problem:

When opening the legacy map in Biotics (NOT the NEW Map), only the inset map displays. The NEW Map works as normal, with the map and all layers loading successfully.

Cause:

A custom layer defined configured to Add to Map in the Map Library is undoubtedly the culprit. In the following example: https://services1.arcgis.com/BkFxaEFNwHqX3tAw/arcgis/rest/services/FS_VCGI_OPENDATA_Cadastral_PROTECTEDLND_poly_SP_v2/FeatureServer 

the problem is that they haven’t specified an individual layer ID - note that lack of a trailing /0 or other layer ID.

If you try to configure the map library so that a feature service URL which lacks the trailing layer ID is initially added to the map (even if it isn’t visible), this will cause the map to fail to load.

Solution:

Deselect Add to Map in the Map Library for the layer so that it is no longer added to the map upon opening. Note that it can still be selected by adding a map resource from the map library.

Alternatively, add /0 to the end of the URL so that the map library entry refers to a specific map layer.

Identify the Problematic Layer:

If the legacy map doesn’t load but does load in the NEW map, it’s usually a custom layer. Determine the problematic layer by first disabling all layers that are initially added to the map through the map library. Make sure the map loads. Then add the layers back one-by-one, refreshing the map in between each, until the error returns. The last one you added back will be a problematic layer; disable it. Continue to add the remaining layers in this same fashion to make sure that none of the other ones are problematic.