Federation in general seems like it’s been flaky as hell ever since a month or two ago… my guess (especially if you see it on some Lemmy servers and not others) is that it’s delayed and will show up eventually.
It’s possible that there’s some unexpected behavior that leads it to federate some places and not others, but my expectation is that once your comment is on lemmy.ml’s server, it’s federation delay between the Lemmy servers and nothing to do with you specifically.
Personally I like upvotes/downvotes. Both are pretty useful information to have and those are the two numbers that my brain translates most cleanly into seeing what’s going on.
Also I want to put in my perennial pitch for the software to display a popup or something the first time you vote, saying hey warning your votes are not private on any federated software! Don’t vote with an expectation of privacy.