Could you be more specific? Do you mean bringing older saves to new builds or do you mean starting a save in a build and not being able to play that save on the same build after you've exited the program?
That's strange. You might have some kind of firewall that prevents the creation of the save folder.
https://www.mediafire.com/file/lcni9snphjud88w/save.rar/file
Download and put the folder in that RAR in the www folder and you should have be able to save.