Date fields keep reverting to "Nov 30, -1"

This is related to a previous support post I made:
https://wpgeodirectory.com/support/topic/date-fields-keep-messing-up/

Whenever I edit a post from the BACK-end that does not have a value set for a date field, a value of “Nov 30, -1” is autofilled. If I forget to erase the date field before saving, it shows up in the front end as “Nov 30, 2015”.

If I edit a post from the FRONT-end that does not already have a date set in a date field [and has not been previously edited], “Nov 30, -1” is autofilled. When I erase this erroneous field and save, then edit again from front end, it is now auto-populated with “Oct 15, 2015” (today’s date a month from now?).

My login info has changed, will post in a private message.