This is a story with a happy ending.

I was riding to work Thursday morning and noticed my downshifts were a little difficult. I had to stomp the shifter a couple of times, but upshifting was smooth as usual, though once or twice a little more resistance could be felt. I didn't hear or feel anything that seemed amiss besides the downshifting resistance, so I continued. Got to work, parked, then came out to head home.

Only a few miles in, the stomping had to get much more forceful. This was a little sketchy when I was into ~15 mph traffic for a few miles with occasional surges to 50 mph. I get to my street finally and luckily caught the light. I had to take my turn in 3rd gear, and made it to the next light. I had to kick the shifter like it was a rabid hog to finally get it to 2nd and finally to 1st. Again, upshifting was fine. As I signal for my house, I can only get into neutral--no 1st gear. Luckily I could coast to where I needed to go.

Went out later, still couldn't get into 1st, but I could upshift to 2nd and 3rd...but no downshift from there. At all.

Friday morning, after reading countless explanations like having to pull my transmission, I remembered one which noted a mids to forwards conversion where the shifter shaft and lever were left in the inner primary cover. I noticed that shaft was no longer visible (previous owner had zip tied it to the shifter rod for the forwards). It had flopped down and was resting on the shifter arm on the pivot shaft going into the transmission. I pivoted it up but still couldn't downshift. I pulled the clutch and hit the starter, and the bike lurched forward a little but didn't start. Tried again, started up, and I was able to downshift all the way, no resistance.

Zip tied the lever to the rod like before and took it out for a five mile test ride--back to normal.

TL;DR: If you can't downshift and converted from mid controls to forwards without removing the mids lever behind the inner primary...that may be your issue.