Animation Sequences did not work after creating Animation Montage.

I uploaded an asset and it had a character and a lot of animations in it. And I wanted to create Animation Montage to run these Animation Sequences with the Play Montage command. I did it, but while the Animation Montages, which were converted from the asset’s own Animation Sequence to Animation Montage, were running, I could not run it with the Play Montage command when I right-clicked on the Animation Sequences in that asset and made an Animation Montage myself. Can anyone help if they know why?