Who builds in an irreversible feature?

You apparently can no longer use the brush on top of stamps. To fix this, you have to flatten the object to use the brush on top of it. This doesn't warn you, though, that it cannot be undone. Well somehow it flattened my entire map and now I cannot edit anything from the HOURS of work I have put into it. I have googled it and am being told that it is irreversible and cannot be undone. I also cannot load an older version of the map because I tried reloading as a fix before I realized what had happened. This mapmaker used to be so great and they ruined it.