Device: Xiaomi 17 Pro Max (Popsicle), Chinese ROM
Firmware: HyperOS 3.0, OS3.0.318.0.WPBCNXM (also tested on earlier builds, same behavior)
Carrier: Türk Telekom (Turkey)
Root status: Bootloader unlocked, rooted with Magisk (init_boot_a/init_boot_b patched)

Issue:
During regular phone calls, the earpiece audio cuts out completely after a variable amount of time (not fixed, ranges from a few seconds to a minute or more into the call). Switching to speakerphone immediately restores audio from the other party — but earpiece audio never comes back for the rest of that call.

What I've tested:
- Happens on every single call when the phone is on 5G (Preferred network type = 5G)
- Does NOT happen when I manually set Preferred network type to 3G/4G only
- Happens regardless of WiFi being on or off (tested with WiFi fully disabled, mobile data only)
- Voice network type shown in status = 4G (VoLTE), so calls are not using VoNR — Türk Telekom doesn't seem to have VoNR live yet
- Happens with earpiece grill clean, tested in Safe Mode (no third-party apps interfering), tested on different days/locations
- Reproducible: essentially every call while 5G is enabled

My working theory: this looks like an EN-DC (5G NSA dual connectivity) issue — the modem is maintaining simultaneous 5G NR data + 4G VoLTE voice bearer, and something in that dual-connectivity handling causes the audio path (not the call itself, call stays connected) to drop on the earpiece specifically, while speaker output is unaffected.

Has anyone else with this device (or other recent Xiaomi/Qualcomm SM8850 devices) on a 5G network seen this? Wondering if this is:
1. A baseband/modem firmware bug specific to this chipset's EN-DC handling
2. Something carrier-specific to networks that recently rolled out 5G (Türk Telekom went live with 5G on April 1, 2026)
3. A known HyperOS 3.0 audio routing bug

Any pointers to a modem firmware fix, a related bug report, or diagnostic steps (e.g. via *#*#4636#*#* or similar) to narrow this down further would be appreciated. Happy to pull logcat/modem logs if someone can point me to what to capture.