Chrome Version       : 62.0.3202.82 (Official Build) (64-bit)
Chrome OS Version    : 9901.66.0 (Official Build) stable-channel chell
URLs (if applicable) :
Other browsers tested: N/A

Brief Description:
I'm currently using SSH mounts and port forwarding to mount a remote machine and forward an IRC connection. I've been using them both in the same configuration and I've noticed that the local port does not seem to be correctly closed upon SSHFS unmounting. I've attached reproduction steps here.

What steps will reproduce the problem?
(1) Open Secure Shell app
(2) Select "[New Connection]"
(3) Type user, server, port information (e.g. macaroni@mymachine.domain.net:22)
(4) Enter SSH Arguments: "-L 6667:localhost:6667" (NB: I'm using this to connect to an IRC bouncer but this works with any port).
(5) Enter mount path (e.g. "/home/macaroni")
(6) Click "SFTP Mount"
(7) Secure shell says "Mounted!". Notice mount occurs, attempt to connect to port using an app (NB: I'm using CIRC to connect to "localhost:6667" and I'm able to interact with my IRC client")
(8) Press "x" to close the window.
(9) Open Secure Shell application
(10) Select previous connection and click "SFTP Unmount"
(11) Notice unmount happens and port is no longer accessible.
(12) Click "SFTP Mount"

What is the expected result?
Remote directory is mounted locally and port forward completes. Secure shell says "Mounted!".

What happens instead?
Secure Shell hangs at "Loading NaCL plugin..."

Please provide any additional information below. Attach a screenshot if
possible.

I debugged this with our local IT staff and it appears that the connection is not being closed correctly when using SFTP mounting. Port forwarding and SFTP mounting work fine independently and jointly on the first run. Subsequent runs will fail.