Front end editing show blank page

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I have found something strange, disabling the plugin S5 Flex menu gives an error message about the router of the pagebuilder, and with the plugin the source code is cut off and not rendered like something breaking in the template

now tested with protostar, the page is loaded with the interface but nothing works.

I can not tell you what is excatly the problem, but there is probably a conflict with something else.