[Selling Pro1or Pro1x. Please no requests for devices, only post if you have one to sell yourself.]

You keep posting these "selling it" threads. Are you expecting a positive response, or what? 

Wouldn't be surprised if the mods lose patience, this is practically the opposite of constructive discussion. 

[Pro1X - problems with bottom=right loudspeaker - repair guide.]

@Mysti-Que2020 No update notification whatsoever, but I haven't touched any default Google Play settings or anything. Presumably it's doing all sorts of updates on its own.

Especially with the corroboration from @Rob. S., I'm more convinced it was a background software update that fixed the bug. The bug was so reliable, persistent, and reproducible beforehand, and now it's just completely gone without a trace. Considering that F(x)tec straight-up stated it was a firmware bug, and said that they had a fix coming, I'm inclined to believe them.

I haven't really done much to the phone since receiving it, so it wasn't anything else that could have fixed it. It's just been sitting on my desk this whole time. (Patiently waiting for a Google-less OS to flash.)

[Pro1X - problems with bottom=right loudspeaker - repair guide.]

Hi! I also had this exact issue, and contacted support. According to F(x)tec, this is a known firmware problem, and the update is on it's way. No need to take apart your phone.

In fact, a few days ago, for me this went from being a reliably reproducible and persistent issue, to suddenly vanishing. My phone's sound now works perfectly at all volume levels. Either the problem is transient after all, or there must have been an update automatically pushed through. I'm still running the stock android OS that came out of the box.