I just thought I'd throw this out there in case anyone has this problem. It's happening on both my phone and my wife's phone. She also can't send her bitmoji's. I don't use them. I called T-Mo support after doing all I could and found out that it's a known issue. It started after the last security update. It only happens when you use any third-party texting app. We both use Textra. The workaround, for now, is to use the stock LG messaging app which isn't that bad. I actually like it. It has a dark mode and that's all I really need. So if anyone has this issue, hang tight, try the workaround, and wait until they have a fix for this. I'll update this if the workaround doesn't work. So far it has but so did Textra, for a few hours, after we restarted the phones.