I have had mine do that a couple of times too. I'm not sure what I did to get it to work right. I think a time or two I moved the fabric too fast. I do remember re-threading both the bobbin and the top as well as cleaning the machine of all the Lint I could find. Never tried using the little "arm" on the bobbin case. I do thread my bobbin thread through that "arm" when using the embroidery unit.
I don't have a lot of experience with my BSR foot, I've used it several times but I haven't used the BSR for a couple of months due to shoulder surgery and not being able to do the actual quilting yet.
Hope you get the issue figured out soon!!!