Hi Glenn thanks for your comment. Indeed, it happens to me a lot of times. The thing is, it depends if those users have already voted for your post in the past. The chances are that bigger upvotes get drained quickly.
Other chance, is that unless you are ranked as excellent in the whitelist those with the higher upvotes, are reserved for that rank; hence, you do not fall into that.
I think the 100% secure one is the "Highest vote for everyone" one.
Cheers and, I liked your mix of MTB and cryptos. I wish I get some beautiful weather soon to go Nduro and MTB :D.