Boards set incorrect URL at URL bar

Troubleshooting
#1

Summary
I am using mattermost via reverse proxy. The URL to access mattermost is:
https://mydomain/myhost/mattermost

By selecting Boards on menu, Dashboard is displayed successfully. But URL is set as https://mydomain/boards/dashboard in URL bar.

Reloading the page, reverse proxy returns HTTP 404.

Steps to reproduce
Run Boards under reverse proxy emvironment.
Mattermost: 6.1.0
nginx(reverse proxy): 1.12.2

Expected behavior
URL is set as https://mydomain/myhost/mattermost/boards/dashboard

Observed behavior
URL is set as https://mydomain/boards/dashboard

#2

Would you be open to creating this issue at Issues · mattermost/focalboard · GitHub?

#3

Thank you. I did.