Mounting ReadyNAS Share over SSHFS

So... my friend and I were in the local Good Will a few weeks ago, and we stumbled upon a ReadyNAS 2120 for $25. They had no idea what it was, nor how (or even if it worked). They let me plug the power in to test it and the lights came on, so I crossed my fingers and bought it.

Long story short, after much trial and error, after verifying that the HDDs were still good, I was able to get it running, successfully updated the firmware to 6.10.10, updated the built-in Plex, and got all my movies and TV shows moved over.

The problem I'm having now is that I want to mount a specific folder (~/src) from the 2120 on a couple local Linux Mint boxes which share a couple source code projects. I figured the easiest way was to simply put all the projects on the NAS, create a special "code monkey" share for them and automate the mounting process by generating an ssh keypair (which I did with ssh-keygen -t rsa -b 4096) and adding a line to /etc/fstab to load the share on each boot, but it isn't working. Each time I try to mount the project folder from the NAS on a machine, I'm prompted for a password - which the SSH key was supposed to eliminate.

From the web interface of the 2120, I imported the key as the KB article here describes, which was accepted by the 2120 with no issue:

And I've added the following line to /etc/fstab based on this Ubuntu article, since I use Mint (an Ubuntu derivative):

coders@10.42.2.95:/data/Code_Monkeys/projects /home/[LOCAL_USER]/src sshfs x-systemd.automount,transform_symlinks,identityfile=/home/[LOCAL_USER]/.ssh/media_server.rsa,allow_other,default_permissions,idmap=user 0 0

I've also tried mounting like this, again to no automagical avail:

coders@10.42.2.95:/data/Code_Monkeys/projects /home/[LOCAL_USER]/src sshfs _netdev 0 0

I can mount manually, which is a good thing, but I want it to mount automagically on boot using the SSH keys, which it isn't doing. Both fstab entries seem to work, but both require me to manually enter the password.

TLDR; Is the problem likey on the NAS or the local machines trying to connect? I need a debug option. Is there a way for me to watch step-by-step what happens to see which side the problem is on?