Coursepress Pro does not save units

I have started adding units to my new course. Added a few elements, clicked “Save” under the elements, clicked “Save” under the unit. Then I visit the list of courses and see that I have 0 units. Repeated multiple times: clicking “Save” makes the site think for a second, looks like success, but units are not saved.

Previewing changes works fine.

Another bit of information: interestingly, I also see 0 units in the default course ” Aenean auctor nec magna sed mattis”, even though I do not remember deleting the 3 units that were there originally.

Using CoursePress Pro v in WordPress 4.4.1.