Text forwarding has stopped working

Text forwarding with my iPad is broken. All texts I send from it to non-iPhone users say not delivered, even though they tell me they are receiving them. None of their replies are showing up on my iPad. I have checked, double checked, and triple checked all settings. iPhone users messages are synching just fine. This all started this morning when I turned on my iPad after having not used it for about three weeks. I opened messages and noticed that NONE of the messages I had sent during that period were synching. Not even iPhone users messages. I also started getting messages on my other devices that said I had logged on to a new iPad. I’ve had it for over five years!!! I was also already logged in to my Apple account, as always. I contacted Apple support via chat and they were unable to help me. This is SUPER frustrating. Is anybody else experiencing anything similar? Thoughts? And just as an FYI, running ios 13.6.1 on iPhone and 12.4.8 on my iPad (both devices completely up to date)