Hi
I have no idea what I have touched, but now when I load any tool, the Undo History appears always empty. (I have checked with multiple projects and the same thing always happens)
I have checked the preferences and everything seems to be correct. ( Enable Saving - activated / Skip Loading - Deactivated)
Anyone know what may be happening?
I’m still using the 2018.1 version
Thanks
Well, first off, don’t do that. 
Upgrading to the most up to date version is free for registered users, and you miss out on a lot of new features and fixes by not doing it. Also, obsolete versions are not officially supported, which means you’ll be on your own for any issues. Be sure to pick that up!
To your question, if your issue is that tools and projects don’t have an Undo history when they are loaded by default, this is normal. When saved, undo histories are saved for every subtool loaded into a session, and can quickly bloat file size. Especially large files may start to experience performance issues. So this is not something you want to do casually, unless you have a need for it.
To save an undo history, it has to be enabled when saving the file (File > Save As, with “Undo History” active.) It also must be enabled in the preferences. Preferences > Undo Histoty > Enable Saving". Remember to store config after making changes in the preferences menu to have the changes persist on each startup.
Remember that undo histories are saved on a per subtool basis, so you have to have a specific subtool active in order to see the history for that subtool.
Thanks Spyndel but my problem is that Undo History was working perfectly and suddenly stopped working.
File > Save As, with “Undo History” is active and Preferences > Undo Histoty > Enable Saving is active too.
But when I load a tool, any tool, tools that I know for sure that had undo history (I checked lots of my recent/old projects) I always have the same result No Undo History (Only one square in the Undo History selector in the top of the document)
Undo histories are only saved as a part of a .zpr (Project) file, and are saved/loaded via the File > Save As/ Open menu.
For any issues beyond that, you are first going to need to update your program to the most recent version. We can’t troubleshoot effectively if we have to factor in issues with obsolete versions as well.
Hey buddy,
I have the same issue,
If you find any answers would you please share here.
Thanks.
Hello
If someone else has encountered this problem, then just save your subtools as Ztool and paste into a new scene
Good luck.