No custom location possible!

Checklist

• Have you pulled and found the error with jc21/nginx-proxy-manager:latest docker image?
  • Yes
• Are you sure you're not using someone else's docker image?
  • Yes
• Have you searched for similar issues (both open and closed)?
  • Yes

Describe the bug

I cannot define a custom subpath. Today at noon everything still worked, but not anymore. I have reinstalled NPM, same error. What is the reason?
When I put it in like this, the entry goes offline. If I take it out, it works again. It seems to be a syntax problem. I can't explain it any other way

the npm container is in the same network as the apache2 container. [-> before it worked the same way. it also does not work if i replace "apache2" with the ip of the container]

Nginx Proxy Manager Version
v2.11.1

To Reproduce
Steps to reproduce the behavior:

1. Add"Custom Location" Entry

Expected behavior
The entry does not go offline

Screenshots
see above

Operating System
Debian with Docker

Additional context
no

Start by reproducing the Custom Location entry from v2.11.1 with Nginx Proxy Manager and the apache2 container on the same Docker network, comparing behavior with and without the custom subpath. Confirm the exact configuration or error that causes the entry to go offline; done means the custom location remains online and forwards successfully.