I've checked that my feed dogs are up, that the tension is on, that my
bobbin is in the correct way, and that the upper thread is correctly
threaded. Is there any other issues I should investigate before
getting my machine looked at?
So as to not be redundant, since you've checked most of the stuff that would go wrong first I suggest the following:
Needle point is important, be sure when sewing wovens you are using a needle with a sharp point (knits use ball point). The size of the needle is crucial.
The weight of the thread may be too thick for this woven fabric.
The bobbin tension with this thread could be part of the issue. Try a different thread in the bobbin and topstitch with the thicker thread. Sometimes that's a good workaround for thread thickness. Different machines have the option to adjust the tension on bobbin casings.
Clean the bobbin holder and the entire bobbin area - no lint whatsoever. Test the machine with this thread and needle using muslin. Is this happening with other woven fabrics and other thread? If so, the timing is probably off. A tune up would be a good way to go.