For the last 3 days or since last patch, have not been able to activate any building or machine. Several are having this problem. It gives error message that you are inside building and will not activate while in building. You get this error message whether at plot marker activating or outside building/machine. Now I have found a temporary fix to this. Since this game is so "bass-ackwards", do the exact opposite of the error message. Go into newly build building or machine near center and activate. It works. Try this solution for now.
DEV: This issue has been fixed and will be patched shortly