Can’t send MMS and can’t receive group texts

Looking for help. iPhone 15 Pro Max. No issues with iMessage. Can send and receive photos. Group iMessage isn’t a problem. Can send group text to non-iMessage (green contact and contacts). When someone in the group responses they come in as individual SMS messages. Cannot text photos to green contacts. In other words, MMS issues.

Previously had no issues receiving group text messages including green contacts. Previously had no issues sending photos to green contacts. MMS was working fine.

Started having issues after adding a data only South Korean local eSIM during travel last week (SK Telecom). Could not send MMS while in Korea even with Korean eSIM off, on airplane mode, WiFi on, and with Verizon eSIM on. (I have used wifi calling since getting the phone).

I have tried the following (including with Verizon and Apple tech support):

* deleted all eSIMS * reactivated Verizon eSIM * switched Verizon eSIM from IMEI 1 to IMEI 2 * reset network settings. * toggled on and off picture messaging through Verizon account (block service) * Verizon tech support restarted MMS and data and phone call. * toggled on and off iMessages * toggled on and off SMS and MMS

It sounds like blocking and unblocking picture messaging or having Verizon restart MMS should have fixed this. But nothing has worked.

Any thoughts?

EDIT: I bit the bullet and decided to do Reset All Settings (Settings --- General --- Transfer or Reset iPhone --- Reset --- Reset All Settings). This fixed my MMS issue. My guess is that when I inserted my Korean eSIM, it changed the APN. But when I deleted it and started using my Verizon eSIM again, the APN didn't change over correctly all the way. Not sure why resetting the network wouldn't have fixed it. But we seem to be good now.