Joining other unlisted communities with an account registered here?

I was trying to search for [email protected] so I could subscribe with this account. However, I couldn't find any of the midwest.social communities aside from the synthesizers one. Is that by design, a bug, or am I doing something wrong?

My process: open Communities. Search [email protected]. I leave the Community and Creator fields set to All. Search again as I've seen some people instruct to do. Nothing populates.