|Making buttonholes in fleece is surprisingly hard on a machine with a 4-step buttonhole (for me, at least). The left side stitches well, but you may find that the machine would rather eat the fleece than sew back up the right side, even after interfacing.
To make the right side cooperate, slip a sheet of notebook paper carefully between the fabric and the plate right before you sew the right side. This is if you donít have/donít want to deal with water-soluble or tear-away stabilizer. I'm still too intimidated to use either.
IMPORTANT: sew the first/left side and bottom bar tack WITHOUT the paperóotherwise, it will shred. After youíve sewn those, raise the needle and very carefully slip a sheet of notebook paper between the fabric and the plate, without disturbing the fabric. Shift your dial to Part 3 of the buttonhole, lower the needle, and stitch up the right side. Then sew your final bartack and secure with 0 stitch length on straight-stitch setting. Tear the notebook paper away.
I found that notebook paper worked better for me than tissue paper, which my machine loves to eat. Yummy.
And always test on a scrap first!