Courses in Garmin Connect not syncing to my Garmin Edge 25

Well, I checked both files, they are of the right type, and I can place them directly on my watch without any issues. Hence there is probably a problem on your Edge. Check whether there is sufficient free room on the storage. Delete all files in //GARMIN/Activities, and old courses, workouts, unused languages in //GARMIN/text/, and then try again. 

Thanks for trying trux, there is definitely sufficient storage, after the last reset it cleared everything, it has 95% free storage when I view it in Windows/PC.

This only seems to have happened after a recent update that I noticed Express was notifying me about a month ago, just blindly went ahead with it, was working fine during summer/autumn, I had recently learned how to use the courses function and was really taking advantage of it to explore/navigate new areas

If you suspect a bug in the firmware, then ask on the Edge 25 forum (https://forums.garmin.com/sports-fitness/cycling/f/edge-20-25). If it is the case, then others can confirm or exclude that suspicion. Otherwise, I recommend contacting the Product Support at https://support.garmin.com, since the files are all right. 

thank you Trux, I found this thread https://forums.garmin.com/sports-fitness/cycling/f/edge-20-25/354251/unable-to-upload-courses/1709607#1709607 I don't quite know why this thread was started in this sub forum - i think I was guided here while using my phone. Definitely seems like a firmware/update issue. Thank you both for your help, and merry Xmas to you guys

I've moved your thread to the Edge 20/25 forum.