Hi @rdobler,
I came across this unanswered question while doing a community cleanup. In case this is still an issue or an issue in the future, I wanted to give a quick reply. As a Canvas admin myself, I strongly suspect an integration between your school's student information system (SIS) and Canvas is the culprit here. There are many systems that sync enrollments (especially student and teacher ones) hourly/daily/weekly and remove any enrollments from Canvas that are not in the SIS. I would guess you're not officially listed as an instructor for the discussion section, so even though you keep getting added, the integration scripts keep pulling you back out. I would suggest contacting your local Canvas administrators (usually in the eLearning / IT / Digital Education areas) if this happens again so they can investigate and hopefully come up with a solution to keep you in the discussion section (assuming it's allowed).
I hope this delayed response helps!
-Chris