I have the same errors as this post:
Canvas is completely empty, but the structure remains - Bugs - Bricks Community Forum (bricksbuilder.io)
It only happens when I start optimizing with the plugin, I don’t know if the same thing happens with wp rocket, or asset clean up.
I was able to fix it temporarily, there are times when the options to add an element appear (like when you create a template and it is empty), but if I change something in the structure it seems, suddenly the canvas loads showing the content, but it only works when it shows to add an element, if it appears totally empty it doesn’t work.