Same issue here -for over a year!- with my XA2 single sim, KPN.
Already since Sailfish OS Seitseminen 3.1.0.11 when i wasn’t really aware so reboots might have solved it at that time.
Since than i went through every available update, right now i’m still @ 3.3.0.16 awaiting the fixed 3.4.0.22 but the “no audio in either direction issue” is always there !
Rebooting -even several times- doesn’t make any difference …
The only inconvenient way to make a phonecall is by use of the build in handsfree loudspeaker so everybody in my vicinity could join my conversation …
Pretty useless for a phone right ?!
Will this EVER get fixed ?!?