After further review, it appears to happen on some of the channels. For instance, on 70's on 7, I CAN add artlsts/song seek. But on 80s on 8 and 90s on 9, I can't. :scratch:
I'm pretty sure this has to do with where these stations are coming from now.
Before Sirius updated their channels, but after XM did, there were some of XM's channels that were sirius named, but were NOT playing the same songs as their sirius counterparts before the update. For example, Octane, Lithium, and a few others did not sync up. Both stations had the same name, but different songs.
It was believed that those stations were being run from DC now, and after the Sirius update, the synced up, which pretty much proves XM's DC control center is running those stations. Also, this is proven further since Octane is one of the few stations being programmed by XM people, former Squizz programmers. So, there's no doubt that this is coming from XM's computers, which means incompatibility with Sirius tuners probably.
Alt nation hasn't changed one bit, and must still be from Sirius' computers, and I'm able to do artist seek on that channel. So, whichever channels are from DC, you can't artist seek, whichever are from Sirius, you can.
Just my theory.