Ampache update with reverse proxy path failure

[stephen-d-hill]

I am using a docker image, within an LXD container called 'ampache', with ampache.cfg.php setting of
local_web_path = "http://localhost"
web_path = "/ampache"
so that I can access ampache publicly on the WAN using https://xxx.xxx.com/ampache/ via the following apache reverse proxy:
<Location /ampache>
ProxyPass http://ampache
ProxyPassReverse http://ampache
</Location>
This works fine.

But when I recently updated the docker image to the latest version and navigated to https://xxx.xxx.com/ampache/, it tries to update the database, but changed the URL to https://xxx.xxx.com/update.php which fails to find the file as '/ampache/' was missing.
So seems this update process is not using web_path from the config file?

To fix the problem I navigated to http://ampache/update.php on my LAN, which performed the update and then I was able to access https://xxx.xxx.com/ampache/ as normal and login.