Can't add series to completed list

I'm trying to mark a series as completed, but when I go to do so, I can't select it. 

If it helps, I checked to see if the problem remained when I selected another series, and I could select it just fine.

 Ji-N:

What series is it? That series may not have an end date. 

https://mydramalist.com/26967-onmitsu-kenshi-season-1 

It only seems to have an end year, I don't know if that matters though.

I'll try to find one and put it in just in case it doesn't,

Well, it seems to be fixed now. I submitted the end date anyways though, just for database purposes.

(I accidentally sent it twice though lol)