I don't think it's just an normal (502) error. The 503 shows the request is bad. And it's just with a few courses but they have always this error.
In a long list it doesn't work and in a short list, not too. But every other course in the list works fine, it's always the problem with the same courses.
Yea, i'm trying to figure out what causes the error and fix it, because it's very strange.
Is it working for slides without any missing ?
No slide support atm.