make sure that everything is proper on the thread (going thru the right spots etc, and make sure the bobbin is right.
Sometimes something will come unhooked from its place.
It looks to me like the tension on the bobbin is loose (if everything is laced correctly).
A bobbin should just hold itself and the bobbin case, when suspended by the thread exiting the bobbin case. Tighten the small adjustment screw on the bobbin case till it barely suspends itself. And rethread the whole machine, making sure everything is correct. Once the bobbin tension is correct, then you can usually just adjust the top tension.
did you switch threads from your test samples?
Different threads will run at different tensions. Adjust accordingly.
Practice on scraps of the same material, if possible, to make sure everything is working right.
edit: I did not see what side you were refering to in the photos, my bad. Still sound advice tho, make sure everything threaded right...
Pedro got it.