Word Press Upgrade - Text disappearing on Visual tab when you Save Draft

I upgraded to the new WordPress version yesterday (or day before) and since then nothing I add to a page, post or my job plug-in stays on the page!

As soon as I press Save Draft, all the information disappears.

If I reformat it, it goes back to just listing it in one continuous string of text (yesterday) but today all the text just disappears and is no longer there.

If I click on the text tab and then visual the information I had inserted earlier will appear

Today when I try it, none of the text is saving when I click Save Draft.

It is rather urgent as I need to post jobs and send out a publication, but I can't seem to change anything.

Is something wrong with the WP editor?

I thought it was one of my plug-ins, but after investigation with the developer over the last day or so it appears all pages are affected and none are working as they usually do.

Is this unusual?

Can someone please check my site or advise how to fix?

Thanks.