Yeah, I was thinking the same thing. Regression testing is an important component of development. I feel very frustrated to have come here because I am having this same issue. I have no doubt that this issue was solved four years ago, but a change to something likely re-introduced this bug. It is driving me bananas. I'm tired of looking down at my watch seeing that my settings have reverted again.
Do you sync on a pc or on the mobile garmin connect, check user settings in both to see what your time setting is 12 or 24 the device is possibly inheriting the value from there
same with any other settings kms/miles
in the mobile app iOS > more > garmin devices> select fr235 > device settings > system
these will be applied on next sync
It has been four years and the same thing still happens to me every time I sync to the garmin connect app (forerunner 35)