Why does a call hang in the asterisk queue?

Question

Asterisk

Good day. There is a problem with hanging calls in the queue. When a call comes into the Queue application, the call is not sent to the operator even if everyone is free. The client is voiced the record "You are the first in line" and so on until the client hangs up. As a result, we get a call with the status "ANSWERED" and with an empty "dstchannel" field.
We use asterisk version 17.7.0. Previously, we encountered the same problem on asterisk version 11, as a result, it was decided to redeploy the PBX on a different OS (Centos 7) and a new version of asterisk.
This problem is "floating" and it is impossible to determine what is causing it. Occurs with a frequency of 1.5 - 2 months and is observed in 3% of calls. I am attaching the log of one of the problematic calls.

log image

https://habrastorage.org/webt/9g/ml/kw/9gmlkwoa4fg...