I think it's a combo of a couple of things, but neither are on the list you gave. First, your level of steem power is a BIIIG factor that goes in to how your curation rewards are (it's honestly one of the few monetary reasons anymore to hold steem power.) I think it was when I was starting to hit around 500-1000 SP (was a while ago) that I would see a reward for 0.001 SP for curation rewards on some of my votes.
The other piece is that there is a minimum for curation rewards, which is 0.001 SP.
So what I think is happening is that your SP is too low to be able to get them. I might've been possible to get a few of those should you be able to get your vote on at that perfect time on that perfect post that got huuuge.
I know it's probably not the answer you were looking for, but is honestly what I think is going on.
Oh yeah dear @sykochica, your answer is perfectly understandable to me. Sniff-Sob-Sniff.
But nonetheless, I will check Ned & Dan pockets to confirm if they don't hold any of my marked coins in there. }:)
Ok, now seriously. I know my SP is very low now as it has always been, however I remember that months ago, when I was exploring and specifically focused on deciphering how to obtain curation rewards, back in time when you just needed to have barely 500-1000 SP to do so. I could not do it, even though I had the ability to do it well according I had the right amount of SP power to get away with something of that. Since on purpose, I also dedicated my time to follow to the letter of the like how to do it succesfully. But without success at the end.
Now, I know that the algorithms have changed drastically after fork 18 and these days you would need to reach way more Steem Power (around 482.398 Steem Power) to have the level & privileges to gain curation rewards. Aaand ¡Go figure! I'm not even gained access to the vote slider bar yet either. LoL
It's a tough one for me to say too in depth without having been there watching at the time. A huge factor in the last couple of months was the whales voting WAAAY less. Just that alone doubled the curation rewards I was getting prior to that.
Some of it has to do with time frame. But it ends up being something that needs to be played with, especially while holding some SP. There are multiple factors right now that allow for better curation rewards compared to before like the fewer whale votes and the share price going WAAAY up. When steem was at 7 cents, there just weren't that many rewards to pay out.
Sorry I can't give specifics on this for you. The best I can offer is to try to build up your SP again and I can follow along this time to see what might be going on.
Right now the slider bar shows up once you have 482.426 or more SP.