Zenfone 8 - ringtone resets itself to zero or not audible

[aussipeter]

Please tell us some basic information before asking for help:
Model Name: Zenfone 8
Firmware Version: 30.12.112.82
Rooted or not: no
Frequency of Occurrence: several times a week
APP Name & APP Version (If your issue relates to the app):
In addition to information above, please also provide as much details as you can, e.g., using scenario, what troubleshooting you've already done, screenshot, etc.
========================================
The headline says it all - the ringtone (settings >Sound & vibration &notification) resets itself infrequently but several times during the week) to being inaudible. I've missed several important calls which is more than annoying. I have the phone for 9 month now and this issue was there from the word go. I did factory reset the phone- to no avail.
Support from ASUS direct or their centers was useless as they only suggested factory reset.
I hope sincerely someone can help as this is an excellent phone otherwise - just this problem alone makes me look at contemplating to buy another Android brand.