The MicroSD card records in 1 minute increments for as long as there is motion, or if you set it to continuous, it will record non stop no matter what. That’s totally unrelated, so I suspect you might be looking at the cloud videos when you think you’re looking at the SD card ones (they’re in 2 different places).
For unlimited, no, it should not stop at 12 seconds. Have you tried doing “reset services” on the cams, and make sure your subscriptions in the wyze app shows the unlimited plan active?
No, you have a micro SD card. A SIM card (Subscriber Identity Module) is something your phone uses for carrier settings (simple answer). A micro SD card is a memory storage card. Completely different animal - other than about the same size.