Maackia, did you check underneath to see if it's a branch from below the graft?
If its not I think you may have a broom or reversion.

I did not look for that, but I will. Here’s a picture of what the buds should look like.

as you say , it stopped developing...elongating

I think I would just leave it ....if it is going to die , then eventually will

I wonder if something is boring at base

ron

Agree with Ron...if you do loose it and cut it out I'd thoroughly inspect for insect activity including under the bark.

Will do. BTW, it’s definitely above the graft line.