Headbutt not working?

[Aeziel]

So went to the johto safari zone to try my luck with skarmory and pineco, but realized headbutt wasn't working on any trees. I ran around johto looking for any 'special' trees meant for headbutting, but found nothing different. Not sure if I'm just dumb, or if headbutt is bugged? 

[Turqueso]

I used headbutt like 4-5 times and It works,at least in Ilex Forest

[Enzo]

Headbutt trees can be interacted with once every 6 hours, regardless of whether they generate an encounter or not.