Building stuck, when placing item in scaffolding zone

Building gets stock when space for planed scaffolding gets blocked.

Steps to reproduce:

  1. Start building
  2. Place item next build area. (In my case it was where the ladder to the scaffolding was suppose to go)
  3. Wait for it to get stuck.
  4. Move object.
  5. Building does not continue. (can be fixed by building a ladder to the scaffolding.

Expected Results:
Tell what is holding up the build.

Actual Results:
Just stops.

Notes:
I my case the ladder to the top of the scaffolding could have been placed at another position.

Attachments:

Version Number and Mods in use:
Alpha 17, no mods

System Information: