Well I will probably be raked over the coals here. I use MAXI LOCK a lot! I love using it for piecing and I also use it for quilting. When using for piecing I use an embroidery needle in my machine usually a 10 or 12. If I use MAXI LOCK for quilting on my domestic machine I use size 14 top stitch.
I have also used embroidery thread for quilting on my domestic using 14 top stitch.
Most of the time if you are having a problem with a thread, it is not the thread but the needle is the problem. The reason I switch to a 14 top stitch needle is to reduce reflection of the needle. Top stitch has a larger and stronger shaft. When free motion quilting, the needle gets "bent" or curved while moving the fabric. With a regular needle it can deflect or reflect against the hole in the needle plate creating an uneven stitch or break. Also the top stitch needle has a larger eye giving the thread a bit more room to move.
I am not one to rule out any type of thread to use until I have exhausted ALL possibilities. Things to try are:
Adjust tension
Change thread path (skip a thread guide going to the tensioner)
Change needle size and type
Use thread net on spool
Flip the spool over
Use spool cap
Remove spool cap
Hope this helps