Phone does not ring. Some times

Using Asterisk 13.5.0 and FreePBX FreePBX 13.0.79.
Phone - cisco spa504G with 7.6.1 fw
Problem: Some times when call comes from queue the phone does not ring.
However asterisk say that everything was ok:
[C-00004fb5] app_dial.c: Called PJSIP/1001/sip:[email protected]:5060
[C-00004fb5] app_queue.c: Local/[email protected];1 is ringing
[C-00004fb5] app_dial.c: PJSIP/1327-00010a4d is ringing
[C-00004fb5] app_queue.c: Local/[email protected];1 is ringing
[C-00004fb5] app_queue.c: Nobody picked up in 12000 ms
[C-00004fb5] app_queue.c: Auto-Pausing Queue Member Local/[email protected]/n in all queues since they failed to answer on queue 2001

Phone monitors it’s state in queue and shows BLF.

So. Users says - that there was no ring, just AUTOPAUSE state changed by itself.

In phone’s call history I see, that caller had reached this phone. However I have no info from phone’s side how long it rung.

Any ideas?