I have had an issue with the latest build 3000 today of a couple buildings not wanting to finish and stopping mid build. Nothing I do seems to get them to finish. I even left it alone went on to hours of play and building later and still not coming back to finish them. 1 is a custom building that walls didn’t finish. the other is the new inn template that was included in the update. No errors are popping up for them at all, and since i can’t currently delete or destroy them to try re-placing them down theres nothing i can do about them at the moment.
Yay, somebody else having the exact same problem I am.
I posted similarly and a moderator rolled my post into the following thread, which I expect they’ll probably do in your case too:
lol yeah except they built the stuff on the mountain minus some walls but the other building is free standing and 1 of the new default templates included in this alpha
oh yay and new issue to add… saying building complete when its not … missing stuff in the design and all the scaffolding is still there.
sometimes slabs don’t add to the main building. Try selecting the missing parts and see if you have to give a build order seperately. As for windows or doors they sometimes get placed after the building is completed. Scaffolting is a know issue 
Seems that something in a17 made it worse
lol the slabs just straight disappeared and everything else is ther jsut no way to get rid of the dang scaffolding now…i added the missing slabs so that’s fixed. I thought A17 was supposed to improve building and fix the scaffolding issue not make it worse.
Having this problem too, even with really simple buildings - most of them are able to finish, but they only take down half of the scaffolding.
it’s issues that need fixed but what i have found as a workaround for now is cheating in a way in my opinion, and thats using console commands to finish a building or destroy a building and individually selecting each ladder and piece of scaffold and destroying them with the console command. ctrl + c opens console ib = instant build and destroy = destroying the item , building, or thing you have selected