I highly doubt your feedback was removed if it was legit. HIGHLY doubt it. Namely because I've had numerous arguments with King Achilles, the moderator, on what is valid feedback and not, as I've had feedback left on other people deleted a few times.
I don't hesitate to hand out negatives, nor do I hesitate to contest false negatives. For example, I got a negative feedback that said "Moans when he is attacked, moans about the dice, moans about pretty much anything and everything except his own shortcomings. Not a pleasant person to play against and thankfully is now on my ignore list," but in reality, all I said was "fucking dice, lost a 9v1 aslkfjslkdfj would have won, who the hell loses a 9v1," you can bet your ass I'll contest it, because I never once said jack shit about getting attacked, nor did I moan about anything else. So if you leave feedback, make sure every part of its accurate. Most of my feedback I get says something like "whines/cries when attacked," etc. yet it's a stupid move on their part, such as me having 15 armies on the field, yellow having 18 armies on the field, and him autoing a 12 vs 12 on me, and having Teal come up with his 30+ armies and kill me and take my cards. So I'll leave a negative feedback for something like that, and I get the "whiney player" feedback back. And that is actually legitimate (I have a LOT of them too) because I did complain.
The biggest flaw with the feedback system is the retaliatories. I went to 43 positives without ever giving a negative. I finally was in a game with such a jerk, I left my first negative, and got one back, obviously he gave it just because I gave him one (he lied in chat multiple times to get another player to attack me in a FoW game). Ever since then, I got over the negative feedback thing, and I'd say that 75% of the time I give someone a negative they give me a negative back. I'd say I've only EVER gotten 2 negative feedbacks that I myself didn't hand out first, or that I wasn't planning on giving a negative to, as I don't give retaliatory feedbacks to (both negatives I got I didn't give either back).
So that's the biggest flaw of the feedback system, people won't give others negatives even if they didn't enjoy the game simply because they are scared of receiving one themself.