I can't add custom effects based on my scenes anymore

When I try to make a custom effect on my bridge based on a few custom scenes I get this error:

Unexpected response from bridge. Please try again later.

Followed by multiple lines of this:

3-/scenes/lightstates/0-resource, /scenes/lightstates/0, not available

It worked for years, was very happy with this functionality, but now it doesn’t work at all?