Ive had a similar issue.
See en_GB Sound Language Pack Not Working
To summaries: -
I installed the FreePBX-64bit-10.13.66.iso distribution.
We have Yealink T23G handsets. By default G722 is enabled.
Using the default sound pack (English) with G722 enabled it works fine.
If you swap the sound pack on FreePBX to English United Kingdom, you get silence if the handset is using G722.
If you disable G722 on the handset English United Kingdom sound pack works.
This is repeatable.
I would like to use G722. Is there a fix pending ?