Linux snap unison-jz package ssh connection always prompts for passphrase

In looking toward upgrading to Ubuntu 20.04.1, I think I will have some machines on 18.04 for a while. I decided to install the unison-jz snap to prevent a version mismatch. Even though I have an ssh-agent running, I keep it around with keychain , and I am able to login to my remote host without a passphrase prompt outside of unison-jz, it always prompts me for the passphrase for my id_rsa file. I have tried to compare the output of

-v

from both ssh and unison-jz's invocation of ssh (by setting

=
-v

in my preferences file, but I cannot tell what the difference is. Any suggestions for what to do next?