Sitebuilder stuck / no reaction

Hi all,

On our website (https://rideabel.com/) , We have a problem with sitebuilder. Everything I am trying to do, there will be no information or any movement in the plugin. Previously we could adjust everything easily in the live editor etc, but there is nothing now.

For some pages, the tab next to visual / text / (pagebuilder) isn’t even there. On some other pages it says “undefined” like the picture beneath here.

I tried switching all plugins off, nothing helped. I did not try redownloadin the plugin. Are there risks to this because when I disable pagebuilder my website already is out of shape.
We make use of a custom theme, created by a developer. We dont exactly know when this happened. So we are not sure if this is because an update or errors.
I use CSS , widget and addon pack from site origin aswell!

I hope someone knows a solution! Thanks in advance!

Regards,

Frank