Algorithm

My understanding of the discovery tab was that all new islands are given a chance to be seen in “new” or “updated” in discovery, yet my past 3 islands have not been seen at all? Is there some issue with my islands that are causing this, my most recent map has been my highest effort creation with months of work put into it, why has this not been pushed, in comparison to my older works? Just since this happening my understand is very vague as these last 3 maps have all been very different from each other