Studio One 6 crashes with IPlug2 AUv2

[hor-net]

Studio One 6 crashes when loading IPlugEffect AUv2

To Reproduce
Build IPlugEffect-macOS in Xcode, select the target macOS-AUv2.
Open Studio One 6 (tested with Studio one 6.5.1) and load IPlugEffect on a new track

Expected behaviour
the plugin should load fine

IMPORTANT DETAILS

• AUv2
• macOS (both intel and apple silicon)
• IGRAPHICS_BACKEND ALL

Additional context
It seems like there is a crash in the AttachBuffers when Plug tries to copy the AU Buffers to its own internal storage, here's the stack trace:

#0 0x0000000132de5806 in void iplug::CastCopy<float, double>(double*, float*, int) at IPlugUtilities.h:151
#1 0x0000000132de5773 in iplug::IPlugProcessor::AttachBuffers(iplug::ERoute, int, int, float**, int) at IPlugProcessor.cpp:481
#2 0x0000000132db639b in iplug::IPlugAU::RenderProc(void*, unsigned int*, AudioTimeStamp const*, unsigned int, unsigned int, AudioBufferList*) at IPlugAU.cpp:1683
#3 0x0000000132db0aeb in iplug::IPlugAU::DoRender(iplug::IPlugAU*, unsigned int*, AudioTimeStamp const*, unsigned int, unsigned int, AudioBufferList*) at IPlugAU.cpp:2440
#4 0x0000000132db8d83 in iplug::IPlugAU::AUMethodRender(void*, unsigned int*, AudioTimeStamp const*, unsigned int, unsigned int, AudioBufferList*) at IPlugAU.cpp:2208

the pointer pSrc is NULL when the crash happens.

On a side note Studio one 5 works perfectly so there is something that Presonus changed in their implementation, I've already wrote to my contact at Presonus to have some help.

[olilarkin]

thanks, reproduced

[hor-net]

Presonus admit a bug with their AU implementation in Studio One 6.5.1, the say to use VST or stick to 6.5.0. A fix is planned for the beginning of 2024.

We tested our IPlug2 plugins with S1 6.5.0 and they work fine there.