Lately, I've been testing out view exchanging sites like u2b, enhanced views etc. I get past the 301+ mark normally, but sometimes my view count just stops updating/counting. For example : my video has 471 views and then suddenly stops updating. The view exchange sites say that the views have been delivered but my view count is stuck. Then, the views unstuck and start to update again, but then after 400 MORE views (871 views), the view count stucks again. I know these aren't high retention views and are mobile, but they passed the 301 mark. So can anyone explain this for me?