Log Upload Fails

Hey. first of all thanks for the project, it is exactly what i need to keep my old smart scale connected 👍

My BT client is posting data to the sync server api and i get a 200 as response. The User is connected and "HasTokens" is True as well in the UI but the server reports the following:

fitbitsyncserver  | fail: FitbitSyncServer.Services.FitbitService[0]
fitbitsyncserver  |       Unable to log fat and weight
fitbitsyncserver  |       Fitbit.Api.Portable.FitbitRequestException: Fitbit Request exception - Http Status Code: 400 - see errors for more details.
fitbitsyncserver  |          at Fitbit.Api.Portable.FitbitClient.HandleResponse(HttpResponseMessage response)
fitbitsyncserver  |          at Fitbit.Api.Portable.FitbitClient.LogWeightAsync(DateTime date, Double weight)
fitbitsyncserver  |          at FitbitSyncServer.Services.FitbitService.LogWeightAndFatAsync(DateTime date, Double weight, Nullable`1 fat) in /src/src/Services/FitbitService.cs:line 26

Any idea what could be the issue or would it be possible to extend the logging to find the root cause of that problem?