VOLTE issue when using LTE on the Moto G6 Plus Phone

[whirlwinder]

Issue reported as per this gitlab page and the XDA forums:
https://gitlab.com/LineageOS/issues/android/-/issues/3283#note_645651448

A handful of users are experiencing the exact same issue as per the description. In case the issue with VOLTE cannot be fixed by you can you at least bring back the VOLTE slider in the settings so some users can turn it off -> Use LTE and when a phone call arrives the network to be automatically switched to 3G?

Thanks