We get situations where we will get "phantom" calls showing in the queues. For example, it might show "1.<> 00:00:51" Sometimes it will show a full number but when an agent tries to pick up the call, nothing happens.

We are running Fop2 version 2.31.21 on Freepbx 14 running Asterisk 16.
FreePBX 14.0.5.28
Asterisk 12.7.5-1902-3.sng7

The only thing that seems to resolve this is to restart the fop2 service but that is very disruptive as this happens several times a day.

I had this issue with low resources. There are a number of modules in Freepbx that take up TONS of ram and CPU, watch htop and see if anything spikes. iSymphony was the biggest culprit, causing java to take up most of my ram. There were a number of other such as ZULU that I removed. I haven't had this particular issue since.