Newsbox showing date as updated on Jan 1, 1970

[PudzPud]

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?

[lat9]

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?