Submission dates in integrated Google spreadsheets gone crazy.

Strange changes in the submissions on my google speadsheets  integrations are messing all my forms answer managing.

The submission dates were good until a couple of days ago, now instead of year-month-day hour:min:sec is appears some sequence of numbers like this one: 42100.81794

Also the submission date and unique ID now appears in the last 2 columns of the spreadsheets, until some days ago it appeared in the first 2 columns.

This his happening in this 2 forms

http://form.jotformeu.com/form/50414495608356

http://form.jotformeu.com/form/50413999298369

Please try to help asap, this is messing all my bookings

Thank you