This might be obvious, but I've published snapshot builds of a library I'm working on that targets the JVM, JS, and several Native targets. When I add the snapshots as a dependency in another MPP I can access the library just fine in the platform-specific code, but I can't from the common code and I have no idea why

I think you need to also reference it as a dependency in your common source set.

I'm including it as a dependency of my common sourceset, but that's what gives me this weird behaviour