Newsbox showing date as updated on Jan 1, 1970

ZC 1.5.5f
Newsbox 2.2.0

Hi,
My newsbox has been working fine for ages, but recently no matter what date I create the post it always shows on live website as updated Jan 1, 1970. The date on admin side shows correctly so I have no idea whats going on. Have added a couple of images to show what I mean.

Any ideas on how to fix this?

What's the site's upgrade history (and template used)?

I'll note that News Box Manager, v2.2.0, updated its database recording of dates to use '0001-01-01' instead of '0000-00-00' in light of more recent, strict MySQL installations. Was a previous version of NBM upgraded when v2.2.0 was installed?