HADR high worker thread usage
Since your DC is on VM, I suspect you are experiencing poor disk performance. Poor disk performance can result in slower log-write times on the secondary which can result in a slower acknowledgment back to the primary replica from the secondary replica (exhausting worker threads). 

Disk latency on Secondary Replica can cause an increase in HADR Sync Commit process, resulting in the Primary holding open threads while waiting for the Secondary to acknowledge the transaction. 

Please check the error log for Deadlocked Schedulers and collect some IO metrics from PerfMon to see the disk latency and the disk queue length.