Right now, I believe the workaround is to use Zenfolio's web-based uploader and DRAG selected photos from Photo Mechanic to the Zenfolio web application. You can save resized JPGs to a new folder, automatically open a new contact sheet, drag them to Zenfolio, then delete them in PM if necessary. I know it is not ideal, but that's where we are at the moment.
As far as I can tell, the other services have not changed their APIs recently and should still work as intended.
When the next version is available for beta testing, we shall certainly proclaim it loudly here. We are eager to get it ready and restore connectivity with Zenfolio, a site we know a lot of users rely on.
Thank you,
Mick