Are you using the OEM provided adapter? The reason is probably due to the usb-c standard being a clusterfuck and essentially having two different types of "usb-c to 3.5mm dongle":
1. active dongle that gets digital audio signals from the phone, and converts that to analog using an onboard DAC
2. passive dongle that receives analog audio signals from the phone, and simply converts the pinout from usb-c to 3.5mm[1]
If you try to use the latter dongle on a phone that doesn't support that use case (ie. it doesn't contain onboard DAC), it will fail to work.
Passive dongles are the only ones that actually have something to do with USB-C standard, as those allow to simply route the analog connection through the USB-C port. Active dongles are just regular USB sound cards that you can plug into a PC too and which could use a USB-A plug just as well.
1. active dongle that gets digital audio signals from the phone, and converts that to analog using an onboard DAC
2. passive dongle that receives analog audio signals from the phone, and simply converts the pinout from usb-c to 3.5mm[1]
If you try to use the latter dongle on a phone that doesn't support that use case (ie. it doesn't contain onboard DAC), it will fail to work.
[1] https://en.wikipedia.org/wiki/USB-C#Audio_Adapter_Accessory_...