This is a persistent and repeatable issue with my HTC One (Android 4.3) but I can't find any mention of it on forums etc. It would be great if anyone can tell me whether it's a known issue, specific to this phone model or perhaps the HTC Sense UI, or specific to some Android version.
Using the phone as a wifi hotspot with my mobile data plan, and simultaneously making a phone call, is a fantastic capability that I use often for conference calls when travelling. However, when doing this, if I mute the phone mic (using the usual mute button on the phone-call screen), data connectivity is immediately dropped. The hotspot remains alive, the phone call is unaffected, but mobile data is unusable and in Settings the "Mobile data" toggle is ON but annotated with "data conectivity is disabled". Un-muting the phone doesn't bring it back, but ending the phone call re-enables data connectivity which then works as normal.
I've observed this when a headset is plugged in to the jack. I haven't yet had a chance to test it without a headset and/or on speakerphone.
It seems obvious that this is a significant bug, and it's highly repeatable, so I'm amazed that I don't find more complaints about it.
Any ideas as how to avoid (or work around) this?