No GPT-4 Chats On Android

Lately I have a complete non-overlap of features on mobile and desktop versions of ChatGPT. I can’t seem to start GPT-4 chats on Android, even though it works on the web version. This means using the same thread on the phone turns them into 3.5 threads. 4 used to work on mobile as well, but then it stopped. I kept updating because I assumed it was a bug and they would fix it, but now they even removed the setting to pick model 4 from the interface.
Conversely, the web version can’t start Custom GPT’s, which the mobile version can. But then I can only hide those custom GPT’s from the sidebar on Desktop.
Both platforms seem to partially not recognize that I have the paid version, as they keep offering it.
I can’t see what custom instructions I am using or search archived threads on desktop.