We have a lot of base maps available to our users with ArcGIS Enterprise, however, I've noticed something in the Portal Map Viewer which I'm curious if anyone else has experienced...
From my testing, it seems like the maximum number of base maps that will be returned within the Basemaps dropdown in the Portal Map Viewer is 50. As I mentioned, we have a lot of base maps available to our users, (for example, dealing with historical imagery, raster and vector tiles caches based on the application use, etc...) the number of web maps created to be used as base maps, and shared to the group we've designated as being used to display available base maps probably numbers somewhere around 65-70.
I noticed that certain web maps that are shared to our base maps group were not showing in the Basemaps dropdown, so I created a test group, shared them to that group, changed the Organization settings, and the same thing is happening ... only 50 maps are being returned.
I'm wondering if anyone knows if there is a setting buried somewhere in the Portal install files that stores the maximum number of maps returned in the Basemaps dropdown, somewhere we could alter the number of maps being returned to include all of our maps that are shared to our basemaps group???
