So, the SST likes to be finicky, but it's had a hard life in its 93k miles.

Multiple overheats at the track before coolers were installed
Factory Fill
8K changed to Pentosin FFL-2
38K changed to SSP Gold
63K changed to cocktail of FFL, SSP and SSTF
90K changed to SSTF-1

Mods
38K SSP Sump installed
90K Dodson Heated Sump and AMS cooler installed, with CBRD radiator

Around 70K, DFCO in manual S-Sport, 2nd gear above 3k rpm will trigger a pending Transmission Service required warning as it decelerates past 2800 rpm. When it decelerates below 1500 rpm in either 1st or 2nd gear, or comes to a stop in N, the warning goes away

At 85K miles, odd gears were lost randomly after coming to a stop at a light after a 10 hour drive. A quick restart of the engine restored odd gears.

At 93K miles, 1st gear was lost after the usual DFCO pending warning. Car refused to downshift from 2nd into 1st. Putting the stick in D, would lower the car only to D3. Going to manual, downshifting to 2nd and putting the car back into D, would put the car into D2 at a stop. Going to N and going back to D, would put the car in D2 pulling away from the light. Once again, a restart of the car would restore missing gears.

This only happens in Manual S-Sport, I don't believe it happens in Manual Normal, Sport or Auto modes.

EXCEPT:

At the least track session a few weeks ago, car behaved fine in the first session. Issues were limited to street pads. In the second session, however, midway through, the same trans service warning light came on mid-session in Auto S-Sport, with the car seemingly wanting to skip gears. Additionally, on a previous lap, the car had trouble finding 4th gear on a straight before finally engaging, resulting in a loss of 0.4s, according to the data. This was the first instance of Auto modes issues. The trans, however, did not overheat in either session, owing to the Dodson / AMS / CBRD combination. Water temps seemed fine as well.

It seems like the trans is on its way out.

Questions:
Should I rebuild and Sportsman over the winter?
Should I switch to driving around in Auto Normal, instead of Manual S-Sport?

I'm going to test again if Manual Normal or Manual Sport generate the issue. If not, I might just drive in Manual Sport.

No issues driving home in Sport Manual.

Any input would be appreciated.