Clef disappears into the second measure when courtesy clefs are disabled

3c7a69d / Windows7

1) "My First Score"
2) Style -> General ->Page -> Untick "Create courtesy clefs" -> Ok
3) Drag and drop a new clef eg bass clef into the measure 2 (necessarily in measure 2)
4) "N" -> Enter a note in this measure 2

Result: the added bass clef disappears.

- Observe this issue occurs only by adding a new clef in the second measure of each system (ie with "My First Score", into measures 2, 6, 10 etc.)
No issue by applying a new clef in measure 3 and followings in the system (or third measure and followings in each other system)