I have done some search in the Ableton's forum in order to see if a lot of people were encountering this type of bug... and it seems to be the case!
However, the problems are described in different threads (sometimes nothing to do with bug reports... like this thread for example )
May be we should create a thread dedicated to this issue (ie. IK Multimedia/Ableton bug in arrangement view) in the "Support Corner" and try to find out how much "Livers" are having this bug (and above all, why it hasn't be sorted out yet by both companies )?
Cheers,
GilJ.