I am getting the exact same error when trying to load the following track template:
http://forum.cockos.com/attachment.p...0&d=1217006523.
It's a routing allowing to have the midi and audio channels of multitimbral instrument plugins on the same track, meaning midi ch1 is on the same track as audio 1/2 and midi ch2 on the same track as audio 3/4 and so on.
It requires 'Feedback Routing' to be allowed in the project settings, so it might count as experimental, but has worked without any problems for me and others so far.
It is set up like in this pic:
https://stash.reaper.fm/oldsb/56209/R...-In-Folder.jpg
Projects that have this routing do load and not crash, they even play correct. But the realtime playing by midi keyboard triggers sort of attack-clicks but no correct sound on the tracks with this routing. All the other tracks behave as normal and can be played realtime.
A real pity, as I really don't want to do without that routing anymore, it's a real killer and I have seen quite a few envious glances from steinborg and cakewalk users for that feature.
Here's hoping that the issues correlate and this might be solved by the same fix.