Avaia Layout Builder options disapeared after updating Enfold from 3.0.4 to 3.6.

Hello There.
Page is still working and all the content is there, but when I try to modify any page, the advanced editor shows nothing and if I click in default editor it shows a blank page. I am working on a staging site so I which is a mirror from Prod so I know all the content is there.
I would appreciate if you can send me any information to help me sort this out.
When I upgraded from 3.0.4 I’ve got a message: 06/jul/16 Attention: We detected some custom styling rules in your custom.css file and restored it ;
do you think this can be related to this custom.css file?
thank you.