I have a new 255. My software version is 16.19, which was released last month. The default units for my region – including Weight: Pounds – match my preferences, so I did not change them.
I use the Strength activity with Workouts created in Garmin Connect. I observed these issues:
- Workout Details does not display weights
- Weight (edit after completing a set) is displayed in kilograms without units
- Weight is recorded in kilograms: for example, a weight entered as 20.0 displays in Garmin Connect as 44 pounds
Resolution: In System > Format > Units, set Weight to Kilograms and back to Pounds. (1) and (2) are fixed; I have not confirmed (3) yet.