I believe your thread popping out of the bobbin case is due to moving in a direction the machine was not designed for. This causes the thread to be pulled at a slightly different angle than designed.
The first time I FMQ, I used my Viking 990. It did OK in all directions but one, I could go about 345 deg with no problem, but moving within that narrow 15 deg area would almost always cause tension problems, skipped stitches and thread breaking. It was going directly to the left (away) from the needle. If I want a bit up/left or down/left I was ok, but directly left was like I was suddenly on a different machine. Easy enough to work on, except that I'd occasionally forget and "Snap" would go the thread, and I'd have some ripping to do. . . . I'm referring to the direction I was moving the fabric, so technically I was sewing to the right as I moved the fabric to the left . . .