Built in hand quilting stitch....
 

This BL has it, I tried it last night on a piece of scrap....NOT! Just a puckered mess...I do plan on calling the dealer today....I know they LOVE me! ......and ask why? But I thought maybe some here have been successful...

Off hand, if any decorative stitch is puckering, you need to use stabilizer and/or loosen the tension a bit. I would go with a tear away stabilizer.

I have 3 Baby Locks. My latest is the BL Journey. It has a hand quilting stitch that I have used often. It always comes out great. I don't know what the problem is with your machine, but I would contact the dealer you purchased from and I would also suggest going to the store and see if they can point out something you might be doing wrong. I know with the Journey it is so complicated sometimes that I can't find the answers in the 100+ manual. Good Luck.

If this is a hand quilting stitch, then it would be tensioned for a quilt sandwich. The top, batting, and backing. This might be why you are getting puckering with the stitch.

I'm not sure of which stitch you mean. Is it a triple then a single? Maybe your top tension is too tight. I'm supposed to be able to do like an imitation sashiko stitch, using sheer thread, but even my dealer can't explain to me how to do it properly, so I've had no joy with that either.
Perhaps someone here on the Board can explain how it's done.

Machine "hand quilted stitch" worked!
 

I know I posted a previous thread about puckering....well, dummy me didn't have a sandwich under that pressure foot.....so with a sample one it worked after I tweaked the tension a bit more........then I proceeded to do it on the tabletopper I had EPP ...........it's good...i don't like the reflectiveness of the mono thread being noticeable....although this spool was in my stash...maybe there is now a dull one......it was a bugger threading...like working with gossamer, spider web silk.........but now I know how I can use it if I choose to.

But, it's now almost done ( just to bind......today) and no longer a UFO, but a useful thing! Now what to finish next?

A new year coming and I'm still surrounded by "old" projects!

Wish you had posted a photo. You are NOT the only one surrounded by UFOs. I am slowly making progress.

Most of us have a lot of UFOs lying around but some have become invisible (playing hide n seek). I found some just yesterday while trying to organize a few things.

The Monopoly thread by Superior Threads is not as shiny as others. You may want to try that one next time.

The Monopoly comes in two ways - glossy and matte. You, of course, would want the matte finish.