Software instrument issue driving me crazy

[Insuable]

When I closed a session last night, I had a simple instrument track using Vacuum. I had recorded a clip of midi events, playing it back, and hearing Vacuum just fine.

Today I opened up the session and it is like that instrument track will not send midi data to a virtual instrument - any of them. When I open Vacuum I can play notes and hear them directly on vacuum, but in Pro Tools I can't get Vacuum to respond to anything from that track. Playing the song via the transport doesn't trigger Vacuum. Using either of my midi controllers doesn't work - it's like Midi data won't go to any virtual instrument on that track. "Playing" the virtual keyboard in Pro Tools doesn't work.

However, if I add another instance of Vacuum to a different instrument track, it works completely normally and as expected, including with external midi devices.

What I've tried:

1) Closing (without saving) and reopening the session
2) Trying another virtual instrument on that track (still doesn't respond)
3) Trying Vacuum on other instrument tracks (works fine)
4) Making sure the instrument track with Vacuum is set up just like other instrument tracks that all work.
5) Making sure Vacuum is working on other instrument tracks (it is).
6) Taking Vacuum off the track then adding it back
7) Completely shutting down and restarting Pro Tools

Everything else on my system seems to be working normally.

Pro Tools Artist 2022.12.0
Windows 10 with everything set up per the optimization guide
M-Audio O2 Pro Mini
Focusrite Scarlett 4|4
ALesis QS 6.1