Well I was working in this proyect, and when I switched from screen1 to screen2, all blocks from screen2 where deleted, so I panic and pressed “ctrl+z” to undo but nothing happened.
I switched back to screen1 and all seems ok. On screen1, I pressed “ctrl + z” but nothing happened, I switched to screen 2 and all the blocks on screen 1 appeared, with the error message saying that the blocks refer to the components that did not exist in this screen.
I got frustrated, erased all the blocks and rebuilt everything.
Yesterday while working, it happened again. So I looked for a way to recreate this bug.
This is what I discovered, on any screen, press and hold “ctrl”, without releasing change to another screen, at this point you can release the “ctrt” or not and finally execute an undo (with the right click-> undo or with “ctrl + z”), and that’s it, all your blocks deleted, and all the blocks on the first screen will appear.
I hope this helps to solve this problem. I couldn’t find a way to recover the original blocks. But now I know how to avoid the bug. Do not press and hold the “ctrl”.