Kobo Sage doesn't sync progress to server anymore

Hi all,
I just bought the Kobo Sage. Installed KOreader right away of course. Signed up to a server to sync my progress to a kindle I have. At first it worked, then it just stopped. It looks like the sage is not pushing the progress to the server that I signed up to, because when I push the progress to the server and try to pull it on the kindle, the kindle says "latest progress is coming from this device", and sometimes straight up says "there is no data". Not sure what to do. Any help would be greatly appreciated