This sounds like a symptom of something.

Agreed.

Have you noticed whether any other symptoms tend to co-occur with it (especially other things related to mood or emotions)?

Choice numbness is a special case of emotional numbness is a special case of disconnecting from the world. It comes with akrasia and not-akrasia (a thingy that prevents me from doing stuff I explicitly want to, but doesn't react when I throw willpower at it - like running into an invisible wall in a video game). My field of attention gets restricted (I can only focus on one thing and not very much, objects in the center of my visual field become more interesting, I bump into walls), and my thoughts slow and confused. I crumble completely under any kind of pressure, even more than usually. I have to monitor motor control more finely (like moving a leg with my hand to remind the motor system how to move it, or focusing on a particular point and willing myself there). If there's emotional numbness, my emotions will feel sort of like detached objects.

Have you noticed any other patterns in these episodes (how often it happens, how long it lasts, whether it has any particular triggers, and whether anything in particular tends to trigger its end)?

It happens when I'm dehydrated, tired, lacking balanced amounts of sunshine, at the wrong level of socialization, or at apparently random. The general state tends to last , curing it usually involves a complete reboot (change of context, rest, then sleep), but it can go in and out of choice numbness. Pressure to answer cements it.

Have you mentioned it to a medical/psychological professional?

Nope. I've had horrible luck with psychiatrists and therapists so far, and I expect anything doctor-findable would have been found by now.

Thanks!