If you start to place anything (I was placing a long conveyor) and a dialog box comes up (for me it was the "vortex accepts any rotation" popup), the current placement is canceled.
Could probably be fixed by waiting for a few seconds or so break with no placements started/finished/in progress (to not interrupt multiple quick placements / if you're in a rhythm) before showing it (or simpler: just until no current in progress placement).