i tried the recommended solution posted here and i don't know yet if it worked for the phone going into "silent", as that happens to me randomly after powering up my phone in the morning every few days, i'll keep an eye on that. but even after doing that process, and checking the mute button, which was working. i still didn't get a text notification on my lock screen, no sound or nothing showing on the screen. i don't know i miss them until i unlock the phone and see a red number next to the message app. this is NOT the same problem a lot of us are having with the entire phone going silent. my sound can be on and still randomly won't get a text notification. even from contacts that i text regularly. sometimes after a few messages back and forth i will start getting notifications. but then the next day i may not, from the same people. it's completely random and DIFFERENT from the "silent" issue, which i also have. i see people on this thread mentioning both problems confusing them together. they are 2 different problems. maybe related to the same bug i don't know. i did send in a bug report for both issues separately because they are not the same problem. my sound can be fine and yet ill still randomly not get a message notification on the lock screen, regardless of sound being on. i wont even get the banner or whatever it's called at the bottom of the lock screen , i've tried changing the way to get them, like stack, count etc. it doesnt matter, when it happens there is nothing to show on the lock screen... i have another thread started for this particular problem since it was different from the topic here, i have both problems and i see some do here too but posting about it on a different problem thread.. here is a link to the thread i started specifically about the message notifications only...
No message notification on lock acreen - Apple Community