It goes in and out with me. At the moment I’m back at not being able to fix it …
Annoyingly I’ve found that it’s absolutely fine in our debug build, only goes wrong in a release build. This is what we call a Heisenbug - as soon as you try to debug it, the problem goes away! Heisenbug - Wikipedia
Same problem here… Thought I got around it but the problem strikes back. For the moment I complete all the arco’s with writing “nat.” as playing technique as well. Hoping for a fix soon…
Paul told me at the end of the day today that he has been able to fix this problem. We are discussing the possibility of issuing a small bug fix update in the New Year, and if we do so, this fix will be included.
To add to what Daniel has said, the circumstances of whether this bug manifests itself or not is down to a number of factors: the exact location in memory where bits of data happen to get stored when the score is loaded, the phase of the moon, colour of your socks and whether you’re having turkey or goose for Christmas dinner. That is to say it’s completely random whether it happens or not (though there are circumstances that may mean it’s more or less likely to happen on a particular machine)
So should I plan on turkey or goose two weeks from now? 
Lamb! No chance of an arco bug that way! 
Sounds great Daniel, thank you! And I can “live with the problem” for now…
So glad this forum and you wonderful people exist. Having the problem here as well. The score worked perfectly yesterday. Loaded it up today and no arco.
Try using ‘nat.’ instead of ‘arco’ (after ‘pizz.’)
Thanks MarkSealey. Yeah, I’ve been using it after reading everyone’s posts. Still having some trouble though with using the natural articulation because in the expression maps I have natural = my sustain keyswitch. If I put a slur it sometimes doesn’t know whether to trigger my legato keyswitch or to use the natural keyswitch. Does that make sense?