🖱️ What’s happening
Windows has a function that allows for automatic selection of highlighted text.
When enabled this caused the mouse operation in Roof Wizard to operate contrary to what the software was expecting to get in some situations, and subsequently manifest itself as serious issues for the generation of walls.
The mouse was set up to have ClickLock enabled. Unchecked this and everything came good.
I suspect that the only connection between the mouse function and the walls was due to a corruption of the RoofDef.dat file trying to save prior dialog settings.
✅ The fix
Open your Windows mouse settings.
Find the option called ClickLock.
Uncheck / disable ClickLock.
Retry the same Roof Wizard action.
🧱 What it looked like in Roof Wizard
The effect on the walls was pretty bad - a simple square roof was created, and then walls projected down, with half the walls disappearing:
The walls on the left were created first, then the roof added - OK. The walls on the right were from projecting walls down from the roof - not OK.
Tested with walls only and it was OK:
and this had the effect of rewriting the values in RoofDef.csv file (I think), so when the software was restarted, the new RoofDef.csv data was read in and the project walls function worked as designed.