It would make sense if bugs/issues could be upvoted as this would allow people to easily +1 issues without making a redundant post saying, “I have this issue as well.”
Upvoting is allowed, you just need to reach a certain number of posts to be able to do it.. not sure why.
It was definitely disabled before, maybe somebody changed it before you saw my post? (I can now upvote things and I couldn’t before)
Edit: Either way, thanks for checking!