I am using Collector with Portal for ArcGIS with portal-tier authentication. I have several users who cannot see data when a web map is opened. The map is shown in the available maps but no layers are displayed. If I give the user a different iPad and have them login they are able to open the map and all data is displayed. Definitely related to something being stored on the iPad. I can have two users logout of Collector, trade devices, login, and layers are shown. However, once it happens to a user on a device no amount of rebooting, logging out, or closing and reopening Collector will fix the issue.
