My galaxy s9 couldn't register to Verizon network after a system update on Feb 7th 2020, the same SIM card worked fine on another phone, T-Mobile SIM card also worked fine on the s9. There were no problems before this software update.
Yes! but be careful with that updates, I did update mine (a phone I bought on ebay) and it switches from Verizon unlocked to AT&T Locked and since then I am having lots of problems getting it unlocked.
Was your device previously carrier unlocked prior to the update?
Yes it was carrier unlocked, and for further reference, the issue happens with Verizon MVNO - Red Pocket CDMA SIM.
Chatted with Red Pocket Support, it appears that a lot of their customers complained about this update causing problems.
The problem seems to be that in the mobile network settings "LTE/CDMA" is not available from the preferred network, only "LTE/3G/2G" etc. options are available.
@SamsungAdam @sean6 Having the same problem but my phone service is with ATT. My phone is also carrier unlocked. So many people are having this issue since that update but Samsung acts like it's not a problem. I sent my phone to them and they replaced the motherboard. It didn't fix it. The only solution they can give me is to send them the phone I just got back from them. I've been dealing with this since the 7th of February as well. It's very frustrating.