I dont believe thats a bug. I recall having that issue once working with a customer and we did have TAC case open for it, but out of the blue, one day all just started working fine without a single change or version upgrade.
I can tell you, having tested https inspection who knows how many times in the lab, it works really well in R81.20. If you need me to test anything, happy to do it, I actually have windows PC thats behind the lab cluster, with inspection running, so not a problem to do any test.
Best,
Andy