When you export endpoints in a CSV file if an endpoint is assigned to a custom identity endpoint group then their "IdentityGroup" column will be blank in the exported CSV. If they are assigned to a "Built-in" group then it will show up in their IdentityGroup column correctly.
When importing endpoints via CSV file if you try to use a custom identity group in the "IdentityGroup" column of any of the hosts the import will fail with a message of the identity group being "invalid". If you assign the hosts to a built-in identity group the import works fine.
Due to this issue I had to assign a bunch of endpoints to their custom group manually.
