Strip Mining Round Counter (Bugged?)

[(XBOX)Pun Times]

I cannot say for certain this is a bug, and it may have already been reported, but the round counter that occurs for Endless Strip Mining on Deimos does not seem to work properly. The counter stays on Round 1 for many pairs of extractors beyond just the first 2. I have played three separate Strip Mining missions and the first two times, the Round ticked from 1 to 2 after 6 and 10 extractors respectively. The third time, I did 4 extractors (4 total, 2 pairs of 2) then returned to the Necralisk and promptly failed the bounty because I didn't even complete the first round...(Despite completing 4 extractors.)

The mission itself is great. One of the most enjoyable endless missions I've ever played, but this...bug...if it is a bug and I'm understanding that properly, makes it hard to keep track of progress and total extractors protected. If this is a bug, I'm bringing it to your attention. If it is not a bug, could you please explain what conditions trigger completing 1 'round' of Strip Mining?

 

Thanks for your time.