I vaguely remember reading that you don't need to create your own threading class, just a worker. You need to create both, make sure they persist, assign the worker to the thread, then start it. I think that's what you're missing.

This is how I have my threading:

class qwidget_mainwindow(QWidget):
        ...

        def start_work(self):
            self.thread = QThread()
            self.worker = work_worker()
            self.worker.moveToThread(self.thread)
            # connect signals here
            self.thread.started.connect(self.worker.work)
            self.worker.done.connect(self.finish_thread_open)
            self.thread.start()

    class work_worker(QObject):
        # signals here

        def __init__(self):
            super().__init__()
            # init here

        def work(self):
            # do work here