Can't figure out where this breakpoint is occurring

Like the title says, image attached:

Looks like line 349 of juce_AudioProcessor.cpp. Visual Studio should have a ‘stack’ window which shows the sequence of function calls which the program called through before reaching this point.

Are you seeing this in a standalone plugin build? If so, perhaps your audio device is forcing the plugin to start with a different number of inputs than the plugin says it supports. You could try continuing past the breakpoint, and then configuring the audio device to use a different number of inputs (you can click the ‘options’ button in the title bar of the plugin to modify audio settings). You could alternatively try modifying your AudioProcessor so that it accepts a wider range of input channel configurations.

Finally, if you haven’t updated JUCE for a while, it might be worth downloading a new copy of the develop branch. Some changes were made to the AudioProcessorPlayer class recently which allow it to pick more suitable channel configurations for hosted AudioProcessors. There’s a chance the issue will go away simply by updating your copy of JUCE.

That seemed to solve the breakpoint issue, but introduced a new issue that I am unfamiliar with

This is telling you that one of your function declarations is missing a matching definition. Check that your calculateAttackOrRelease function actually has a function body somewhere in your project.

Oh, thank you so much for your help! turns out I forgot to reinstate a section that I commented out believing it was part of the issue

This forum is so helpful!