@Hammy, i had a nightmare with this a while ago, now i've worked out how to muddle through and so here's a guide that's just about working for me.
it takes about 5 times as long as it should and i occasionally forget to copy content before updating, but it is possible to use this plugin with the bug.. although if you have an alternative i'd suggest using it - unfortunately i built my site around this and would lose all my pages if i did.
1. DO NOT TOUCH the preview button, that breaks everything but you wont realise until you try to save.
2. always watch and wait until the page has finished loading before doing anything. if you suspect it's playing games then refresh it before adding anything or updating again.
3. dont have the page you are editing open in a different tab.. i try to have no other tabs running my site. i dont know why but it seems to cause issues sometimes.
4. when you update and blocks have moved themselves to the top, left field it has not saved your work. i refresh the page, wait for it to finish loading, and then move them page and update.
5. copy/paste everything you write into a word doc before updating (the html is more accurate).
6. if you use tinymce and the buttons are not at the top of the page then something has gone wrong and it will wipe your work. (i'm not sure what this is, but it only happens in pagebuilder).
7. oh and if you can set up templates for making new pages and not move things around often that helps a lot.
i hope that is some help.