Does this happen in Safe Mode as well? https://support.t-mobile.com/docs/DOC-29226. If not, then it's likely due to some app you installed -- you'd have to uninstall apps one by one until the problem goes away.
Sometimes, after a factory reset, apps that were previously installed will reinstall automatically (like if you agree to restore the data during the Setup Wizard). Are you certain nothing got reinstalled after you did the factory reset?
One of the updates might be a culprit as well.. I'm not clear on if you actually tried Safe Mode -- if you haven't, give it a try.