Insert editing stopped working this week

I usually edit from stringout sequences in my Source monitor in to cut sequences in my Program monitor. I set ins and outs on the source side, set an in point on the program side, then patch the track I want to edit across, hit period, and bam, the media appears in my sequence. I’ve been cutting this way every day for over ten years professionally. Except this week it stopped working.

I’ve tried resetting all my settings and preferences. I’ve started a new project. Insert/Overwrite work fine when I’m cutting from a raw clip on the source side. But when I put a sequence in the source, enable, say, Audio 2, and try to just cut that one track across… nothing. 

Weirdly, if I enable ALL the audio tracks, it works. But sometimes I don’t want that. I want to, for example, go back to a version of something I had a month ago, and just take the music track, line up the two sequences and ONLY cut track 14 or 16 or whatever, over the newer track 14. Except, now that no longer works.

It’s a real bummer, because it’s central to how I work with Premiere. And how I have ALWAYS worked with Premiere. I make my living by being able to work fast with this software. And if I have to find a workaround to fix something that wasn’t broken before, it will be very, very inconvenient.

I’m using Premiere 26.2.2. The problem seemed to start with this latest update.

I’m on a Windows laptop, Windows 11, Version 25H2 OS Build 26200.8457

GPU is GeForce RTX 50900 Laptop. Studio Driver Version 591.74

Context, this problem affects all my projects (i.e. the Production I’ve been working in for the last six months, but also test projects I’ve created to experiment.)