1) As system admin create a channel-moderated channel with reactions disabled.
2) Create a team scheme channel mentions disabled for members. Do not associate a team to the team scheme. Save the scheme.
3) Observe that a channel member can use channel mentions.
4) Associate the team to the team scheme and save.
Actual: Member can still use channel mentions.
Expected: Members cannot use channel mentions as per the team scheme.
Note1: restarting the server fixes the issue on the server so the cache is not being invalidated upon adding or removing teams to team schemes.
Note2: there and existing bug whereby websockets are not properly updating the schemes associated to teams in redux when a team is added or removed from a team scheme. This has likely been in place since the launch of team schemes. I have filed https://mattermost.atlassian.net/browse/MM-23605 to fix it.