Disappearing parts during overlap happens because the same line overlaps itself. There are several ways to avoid or fix this:

• Don't start drawing at a corner. If the start/end is in the middle of a length of wall you don't need any overlaps
• Build the walls using more than one path. If they are not the same entity, you don't get the disappearing problem.
• Use tools like Combine Path or Path to Poly to combine the lines to make the corners actual corners and not just "meeting points of the ends"

Next one up, this time @Wyverns Cloven House

If that's the result of picking the Mike Schely option during export, then it looks like there is either something wrong with your export options, or the template file is missing.

Can you in the export dialog after picking the Schley export setting hit the Edit button instead of the Export World button. On the first page of the editor, make sure the template is set like this

Also, to confirm the file actually exists as well, hit the button with the three dots there, that should bring up a file open dialog that should show the available template files. Make sure the Mike Schley template is actually among the files shown here.

Pick the_CC3+ Mike Schley export setting when exporting from CC3+. Or, if you have defined your own export setting, make sure to use the @Templates\CC3+ Mike Schley.FCW template file in the first page of the export settings.

This time @Jeff B's entry, The Jenin River Whiskey Distillery have been added: