Sporadic SMS Sound Alerts on 10.2.1

There is no official SMS/Text bug thread so I am disclosing this issue here. I found out that not all my messages come with the sound alert and here are the instances when they occur:

I've updated yesterday but didn't pay attention to it until this morning when I got my phone out of Bedside Mode and saw that my texts are coming in silent.

I've texted myself and there was a sound notification, then I texted myself again and I didn't get any and then again and I still didn't get any sound.

After a restart I texted myself again and I managed to get the sound alert twice in a row and then I texted myself again via instant preview and I got nothing.

Possible conclusions:
1) Bedside Mode breaks the sound notifications
2) Instant Preview reply breaks sound notifications
3) General bug when there are more messages back and forth in short period of time, in other words there is a cooldown for sound alert before it can sound off again

I am using a third party app for notifications and sounds etc. I don't have that problem. but bedside mode DID break it for me a few weeks ago. I switched to Hub++ and its been fine.