ZC 1.5.0 with 1.5.1 cache maria db 10.x nginx jquery 2.2.4 min

Hi Dear Zen Cart folks,

been sick for a long time but now feeling little better and tried to improve one old site to make it load faster with lazy loader.

I used Diva vocals addons and lazy loading works fine on all pages but checkout_confirmation aka. last step fails. This is related to lazyloader script but there is no error messages on chrome dev tools so I am a bit clueless what could be going wrong. On checkout process there is an submitonce() script added at some point but it has worked earlier fine.

Any help would be highly appreciated to haunt this bug down,