Strange behaviour when moving slur anchors after slur creation

Win7 - version 2.0

I came accross a strange thing while moving the slur anchors. It only happens after creation, saving the file and reopening it makes it behave correctly.

- open the highly sophisticated mscz file
- put a slur over C and D

- select start anchor and move it to B -> ok

- reselect the start anchor and try to move it back to C -> NOK

- ... but moving it to A is ok

- reselect the start anchor and try to move it back to B or C -> NOK

(undo to restore the slur from A to D)
- now select the end anchor and move it to C -> ok

- from now on, everything is back to normal, I can move the start and end slur anchors as wished&expected.