I can only suggest going through the notification settings and sounds and vibrations in the phone settings. Is it fot a particular app or apps? I know after the update on one of my phones, the sound was put on silent strangely. Calls and everything.
Not noticed it myself. Maybe it's a bug. Best send feedback in the support section on the Members App Maybe I get the same but im not always around my phone. Or its in my pocket
If you're not using goodlock and have reduced animations turned on while using brief popup style in notification settings it only allows Samsung messages to display notifications on lock screen, I use edge lighting from good lock while have reduced animations turned on Notifications advanced show notifications on all
Apologies if you already tried this, but perhaps toggle off and then on again? I was playing with my notification settings the other day and accidentally managed to stop my now bar from showing, i think there are just so many permutations, so try this then go into the specific app you want to have show on the lock screen and make sure that it's toggled to show content, pop up etc