Skills removing themselves from bars

Hey there,

anyone knows as to why whenever I switch my spec or relog skills just disappear from my bars?
Not all of them, just like 5-6 skills I always have to put back on the bars. I mean, it's not a big deal but quite annoying to be honest.


Thanks.

Are you using an addon for your bars or are you using the default bars?

Does it happen when all addons are disabled?