MediaWiki:Gather-moderation-hidden-email-body/en

Your collection $1 was hidden. This means that you are the only one who can see it. Collections are hidden if they go against the wiki's moderation criteria: https://en.wikipedia.org/wiki/Wikipedia:Gather/Moderation_Criteria

You can contest this on the following page: https://en.wikipedia.org/wiki/Wikipedia:Gather/User_Feedback