In the last few days I got notice that a new version was being - (then had been) - downloaded.
Since then whenever I open PYDT client I have it greyed out, with a window above offering me Update or Cancel options. Pressing Update seemingly has no effect, and I need to press Cancel to get rid of the greyout and access to the client window, where it appears to function ok.
Edit: It thinks it is version 2.0.1 currently.