OSM API /create with empty response

Hello,

https://wiki.openstreetmap.org/wiki/API_v0.6#Create:_POST_/api/0.6/gpx/create

I successfully use this endpoint to upload a new track. Now I want to update this track, but I only get an empty object {} as an answer when uploading, but the ID of the created files should actually be contained there.

what am I doing wrong when intercepting the response?

greetings perry