Direct message to some users fails for one specific user

@aro, can you share the value of the Roles column of the ChannelMembers table for the direct message “channel” in question? The Type of a direct message “channel” will be D and its name will be a composition of the two user ids, but you can probably find this more easily if you just look in the ChannelMembers table for a channel where only you and an affected user are members.