Just a question: was your population quality setting at "highest"?
As far as I think I understood this setting, anything lower than highest will result in some individual instances not being rendered with the full geometric detail. That'a ok for - say - trees, as in the distance, it doesn't matter if a twig or a few leaves are missing.
That said, I could be mistaken, but that's what I would try with your tents first.
Cheers,
Frank