Ideas category vote button missing

The vote button in the ideas category is missing for some threads while present for the others, is there a way to turn the vote button off when you post a thread or is it some kind of a bug?

It depends on where you post it. You can post as voting or as normal thread.

Ahh, that explains it.
Although, I must be blind, where is the magic button?

There are only two voting categories:

Any thread posted there will become a feature request with voting. All others will be just discussions.