Defiler Rewards

So I had been running it for almost an hour and was only getting 4 at a time. But then when I hit 176 and completed it my last run, I shot up to just a little over 300. I was at 7 after I spent it, and I ran it again and went up to 21 from 7, so I got 14 that run. Did it again just now and I got 4 again so I'm at 25. Wanted to know if it was bugged and not tracking properly or if you just get more for a certain amount it solo completions?