While in the middle of quilting, my walking foot occasionally sticks in an "up" position above the fabric as though the presser foot bar has been lifted. Any ideas why this happens or what I should do to remedy the situation?

Check for lint build up.

if you've used it a lot, it might also need a drop of oil... but be sure to wipe off any excess before you use it again.

Thanks - I will check for lint.

Oil - good idea. I've been remiss in oiling anything I use - sewing machine, walking foot, blender, meat grinder, you name it. I will blow out the lint then oil (& wipe off excess) before I use the foot again.

I recently had a walking foot on a relatively new Babylock
machine stick after using it a few hours. The dealer suggested a drop of oil, which I tried & it only worked for a few minutes.

Since it was still under warranty, I took the walking foot in, he showed me how it was sticking & handed me a new one.
He said sometimes they are faulty & stick.

So if yours is new, I would see if it could be replaced if oiling does not fix it.

Thank you - my walking foot is also a Baby Lock, though probably not still under warranty.