Skill never comes if you teach one to fill the spot
If you teach your monster a skill prior to it getting its level up skill ( the one that should come automatically when you reach a certain level), the level up skill will never come nor ask if you want to replace what's currently there. For some of the better epic or legendary monsters, that means you miss out on the advanced skill that comes at later levels which sadly can make all the difference. It's a rude shock to find when you've worked hard to get that monster and level it up, looking forward to that one skill that does 120 or 90 damage only for it to never come.
And do t ask support about it cause they won't get back to you.
And do t ask support about it cause they won't get back to you.