Why don't you upload a screenshot showing the "Vocabulary history", how many words you have learned max?
If you have tested out vocabulary and you hit the maxium, then yes, it could happen that you have finished it already.
I can only guess at the moment....so will probably the Lingvist support staff without any further detail informations from you...
There seems to be a glitch happening now that they're doing the 50 new word limit per day. Once you've reached your limit, half the time it just tells you that you've finished the course instead of just saying that you can't do any more new cards. Or at least, that's been my experience with the French.