QuiltE when that happens to me and it does happen a lot I change the needle, my preferred needle for all sewing and embroidery is a Topstitch 80 but depending on the thread you are using for FMQ you may want to try a 90.
This is what is says in my machine manual
The machine skips stitches
Is the needle inserted correctly
Do you have the wrong needle
Is the needle bent or blunt
Is the machine threaded correctly
Is the needle too small for the thread
It seems it is all about the needle, good luck and I hope you can figure it out..