I suggest the dealership service dept for this. It reads like a defective port or bad connection to it.

 

This isn't something I recall ever seeing listed as a problem here given a known working SIM like the dealer had and with your SIM being verified by AT&T. I agree it sounds like something for the dealer to solve, especially since their "working" sim didn't work.

 

Back in August 2018 JLR reported issues with SIM card activation issues in some cars. It was being investigated. I don't know of a resolution.
UK forum also reported that some cars had to have the SIM card reader hardware replaced.

Is the IMC programming up-to-date? What version of software do you see in the SOTA display? Is it up to at least 19A or did it get the recent rollout of 20A?

 

Thanks for the reply. My ipace is all set now, after they replaced the sim assembly.

 

When we recently had the "data limit exceeded" problem I turned off mobile data. Once I read the problem was resolved I tried to turn it back on after I started up the car next time. When I did it said "SIM not supported" for the same SIM I've had in the car for about a year. After lunch when I went back out to the car it was working fine. So this could be a new bug in S20A where it can't properly read / initialize the SIM unless it happens at boot time.