Perhaps this is a bug?

On opening a song file am_iblue.mgu I look at bar 6 in notation view and see:


The display of Bb and A looks wrong, as you can see if I switch the notation view into staff roll mode:



If I then click Play and Stop and look at bar 6 again in regular notation mode, it is shown differently:



Is there a subtle explanation for this behavior? I have seen similar curiosities in other songs.

John


BiaB 2014 b380, RB 2014 b3, Windows 7 Ultimate SP1, Intel Core 2 Quad, 2.4GHz 4GB RAM 500GB HD. Focusrite Scarlett 8i6 USB, Yamaha WX5, Yamaha VL70m, Yamaha TX81Z, Garritan JABB 3.0, Reaper 4.57