Hello!

i have the following problem and think it is a bug:
I want my users to be able to create a room and set an alias for it, but prohibit them to set the room public in the public server room list.

For this i set the following options in my own Matrix-Synapse 1.12.0 installation in the homeserver.yaml:

alias_creation_rules:
  - user_id: "*"
    alias: "*"
    room_id: "*"
    action: allow

room_list_publication_rules:
  - user_id: "*"
    alias: "*"
    room_id: "*"
    action: deny

With this setting, my users:
Can create an alias for an existing room, but can not make it public

But:
They can create a NEW room and set the option "public" and give it an alias.
The room then is created and appears in the server public room list.

After creation, you can set the option "public" for the room setting off again, but not on again like it should be.

Tested with Riot.IM Web 15.12 and Riot.App 15.14.

With the Riot.IM for iOS it works as it should.

With "alias_creation_rules: action: deny" it works as it should:
Users can not create public rooms nor set them public after creation (and no aliases, of course)

Thanks!