Steps not syncing correctly between Apple Watch and Fitness app after doing stair stepper exercise

So I noticed that lately, whenever I sync my Apple Watch Series 8 to the Matrix stair stepper machine at my university’s gym, the steps don’t sync correctly between my Apple Watch and the Fitness App on my iPhone 15 Pro Max. This only happens when I sync my watch to that specific stair stepper; I don’t know if this happens with other stair steppers from other companies/brands, since the university gym only has Matrix brand stair steppers and I don’t really use the stair stepper at the other gym I go to. On the days that I don’t use the stair stepper machine, my steps are all synced correctly.

Usually, I go for 30 minutes on the stair stepper, which is a little bit over 1000 steps. My Apple Watch counts those steps and they’re included on the watch, but on the Fitness app, my step count will be about 1000 steps behind. All the other data will be correct — the exercise minutes, calories burned, hours standing, miles walked, etc. — except for the steps. Not even force-restarting the app, my watch, or my phone made the steps sync correctly. My iPhone and Apple Watch are both updated to the most recent OS, too, so I know it can’t be the OS being outdated.

Has anyone else had this problem, and if so, is there a way to fix it?