Does Garmin not understand the world is round, timezones exist?

This seems to be a deeper issue in Garmin Connect implementation. I am in GMT+1 and I also experience some oddities. For example, when I add new gear the "first use" date appears one day before (i.e. I enter Dec 5, but when I view it later it says Dec 4). When I break the daily steps personal record, the record is also displayed with a date one day earlier (but all other records have correct dates). I suspect the things that do not have an explicit time of day (like the gear first use date) are stored with time of day set to 00:00:00 local time which gives a day earlier for time zones on the eastern hemisphere when displayed in GMT.

I guess the same is happening to your weight data. Garmin Connect allows only one weight measurement per day and probably stores it with time of day set to 00:00:00 in your local time zone.

And since the issue goes as far back in time as I can remember, I would not expect it to be fixed anytime soon.

I weigh myself with a Withings scale because that's what I have. It records itself in there with the correct date and time. This then transfers to Apple Health with the correct date and time. It then appears in Garmin as the day before.

I'm in Sydney which is GMT+10. I weigh myself about 6am, which in US Eastern time is 2pm the day before. I suspect this is what's going on.

All my devices and systems are set to the right timezone.

I see in the Garmin Index subforum this is a problem that keeps getting fixed then recurring.

Yep me too (i'm in Melbourne) and it's been like this since before i can remember (a long time!). I wouldn't hold your breath for a fix, although i wish they did. One of the reasons why i'll never buy a Garmin scale, because if they can't even get the timezones correct how can i believe they'll manage the rest of my weight data properly and trust they won't mess it up going into the future.

BTW, does the apple health->GCM sync work for you? The only way i've been able to get my weight measurements from Withings into the Garmin ecosystem is through myfitnesspal (Withings->MFP->GC). I also have the data sync from Withings to apple health but it never transfers through to GCM if i sever the direct MPF connection (and yep, it's all set up fine because other Garmin things are reading/writing there).

I also live in Melbourne and all the events from Garmin Connect appear in the Apple Health app at completely the wrong time. For example, my sleep on Friday night shows in the health app between 1200 and 1700 Saturday afternoon - not that helpful!! Garmin can you please fix this!