"Host * IdentityAgent" required to connect to SFTP and "Host customname IdentityAgent" not working

OK, I removed IdentityFile and IdentitiesOnly from the specific host entry in config and it still won't connect in Transmit:

Host customname
HostName domain.com
Port 18765
User username
IdentityAgent "~/Library/Group Containers/2BUA8C4S2C.com.1password/t/agent.sock"


It still only works if I have the IdentityAgent set on Host *. But I can't use that because then it breaks SSH and SFTP with my https://1password.community/discussion/comment/632455#Comment_632455 with DigitalOcean and https://developer.1password.com/docs/ssh/agent/advanced/#ssh-server-six-key-limit.

So it appears that Transmit needs Host * in order for 1P ssh-agent to work, but only for some hosts. My config entries are the same HostName that I am using in Transmit, so I would figure it would see them just fine, correct?

I think I'll have to abandon 1P SSH Keys completely for now. I can't figure out the correct combination of ssh config, which public and/or private keys need to be downloaded and/or loaded in Transmit. It's very possible everything would work fine if I used something else besides Transmit, but I'm not willing to give that up.