1) Maximise the FinalBuilder window. 2) Minimize the FinalBuilder window. 3) Click the FinalBuilder icon in the task bar. 4) FinalBuilder window restores to full screen, then immediately switches to windowed mode (Restore down).
Ok, spent 3 hrs looking for the cause of this, tracked it down to a third party component we use for the trayicon, then discovered there was an update to that component which listed the exact issue in it’s change history! Wish I had looked that up earlier! This build includes the fix :