Ok, you probably got this already covered - but I have to ask - is it running a compatible version of jQuery?
The AdminLTE repository cites jQuery 1.11+ - the current version is at 3.2.1 and a lot of the 1.x shenanigans have be deprecated (npm should get the right version, but where is that jQuery exactly coming from and which version is it actually).
(I hit the jackpot once, so it’s unlikely to happen again.)
