Updates can be pretty finicky, since everything needs to match perfectly for Steam to consider it a valid update. Sadly there's not any real solution for this.

I would recommend just uploading a "X layout updated" as a new workshop item, im sure people wont mind.

Keep in mind if you changed PC's or just user profiles then your previous uploads wont be carried across.

Did you get given any specific error message?

no error message, that layout isn't there to choose from, all good , I'll do the "x layout update" next time , thx