The main instrument with which I know it happens is this jungle kick-bass instrument, which has worked fine for several weeks, until just the other day. Now it plays as if it is drastically pitch shifted up. I have heard a few others doing it but haven't yet established which ones. All other instruments playing at the same time as the off one's play as normal.

It started happening after I moved some instruments around in the string they're stored in, added a side-chain compression bus for most of the basses (but not the jungle bass) and fiddled around with the output sample rate and resolution. As my app is outputting wav files and then playing them back in SDL Mixer, I suspected that it might be a sample rate issue, but I have set all the sample rates and resolutions back to their original formats, as well as some others, to try to fix it and nothing changes

I have examined the pitches being sent to the jungle bass in the c++ app, and they all look normal.