wakapi: Data not send to Api - Failed to send heartbeat

Hey, thanks to the great work. I am using the Windows version. Starting and setting up worked very well. Also migrating the data from Wakatime to Wakapi.

My problem is, that there are no data send to the API. The Log has a fatal error in sending hearthbeats. Datas also wont be send to Wakatime

{
   "caller":"/home/runner/work/wakatime-cli/wakatime-cli/cmd/legacy/heartbeat/heartbeat.go:47",
   "func":"Run",
   "level":"fatal",
   "message":"failed to send heartbeat(s): failed to load command parameters: failed to retrieve entity",
   "now":"2021-06-24T14:11:01+02:00",
   "version":""
}

The API and APP health is both 1.

My .wakatime.cfg looks like this:

[settings]
api_url = http://localhost:3000/api
api_key = 8e5756d6-f609-426e-9a24-85ae59b7c149

Thanks for your help. Developer66