Cannot use skeletal mesh animation

I made a simple animation, it shows fine in that editor. But when I bring it into a blueprint or try and apply it directly to a skeletal mesh in game, nothing plays.

It seems like all the tutorials are about Control Rig which is overkill for my use-case. I just want to make a really simple FK animation.

So, I figured out that I need to use control rig. I don’t consider this really solving the problem, because for my needs Control Rig is overkill (I just need to make a super simple FK animation without controls), but it is at least a workaround.