I believe this could either be a Sibelius problem or a VDL problem but I'm not sure:
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[li]I've got a fairly large score; VDL instruments for the percussion and Sibelius Sounds for the horns - and I constantly run into this problem:[/li]
[li]When I add a full band score to my VDL percussion, funny things start happening with the horns. Either 1) Only some of the horns will play back (usually not the low brass), or 2) Notes that have any sort of articulation on them (accents, slurs, etc.) won't play back. This only happens when I'm using horns under the VDL playback configuration. Is it possible my computer just can't handle that many staves?[/li]
[/list][list]
[li]I have 18 staves so far, and am planning on adding more. Also, there are some instrument changes in my VDL parts which I know can cause some issues. All VDL parts are playing back fine though.[/li]
[/list]
Right now, I'm having to compose percussion and horn parts in separate files and combine them in GarageBand and it is very cumbersome for the writing process. Any help on this issue (if it's in your realm) would be greatly appreciated!

I believe it's on the Sibelius side. Is there anything in the Mixer that doesn't look right?

Update: It seems the playback problems that I mentioned are not consistent. I tried playing it back again after giving Sibelius a few hours rest, and it played back all the notes this time, though playback was very choppy and erratic.

Nothing in the mixer looked weird.

I will direct this question to the Sibelius team. Thank you for pointing me that way!

I'm not sure if this is a relevant solution to look into, but maybe check this out:

https://www.tapspace.com/forums/index.php?topic=4461.msg23329#msg23329

Jim,

Thanks for sending me that thread, that's the exact problem I've been having...unfortunately, it looks like there is no solution. I will do some experimenting, and I'll also ask the Sibelius team - and whatever I find out, I'll post here. I'm willing to bet a few people are having this problem. Thanks!