Map now breaks the page

I’ve been using this plug in for a while, and even bought a license, it’s been working fine, but this weekend the only map we use, with hundreds of markers added to it, has broken the page.
I can create a new map and that short code works and the map appears again, but when I switch back to the short code for the proper map the page is just blank.

This is a fatal problem and if we cannot find a solution for it we will have to start all over again, manually adding hundreds of markers!

Please advise.