As of October 1, Apple SIM is no longer available for activating new cellular data plans on supported iPad models, according to an Apple support document. Introduced in 2014, the Apple SIM was ...
As a last resort, you can sign out of iCloud and log back in. On iPhone/iPad, go to Settings > [Your Name], scroll down, and tap Sign Out. On Mac, go to System Settings > Apple ID > Overview > Sign ...