asterisk users - Feb 2018 - .gsm recordings corrupted when running Asterisk in virtual machine

Hi guys

Has anybody encountered a situation where .gsm recordings are corrupted if
the Asterisk instance is running in a virtual machine?

Specifically running Asterisk in MS Azure cloud VMs on Centos 7 inside the
hosted instance.

Switching to .wav files solves the problem, I can only guess that .gsm
encoding is very time sensitive or reliant on timer behaviour that cannot be
guaranteed in a virtual instance.

Is this assumption correct? Any pointers about how to make GSM encoding work
right on a VM?

Thanks!

Stefan