So I am playing on Lost Island. And a large Dino decided to stomp down some trees around my base. Thing is I like those trees. They keep me hidden away from prying eyes. So I decided to make re-fertilizer. I know it has a period where it doesn't work. I know you have to wait for essentially the respawn timer to count down until the resource would have respawned naturally. I have waited over three real life days now. And I have used about 10 bags of re-fertilizer and the plants are still not growing back.
I have done a few things to reproduce. I have tried a hosting a local instance of ark. And also done it on the official servers. I have tried different locations on Lost Island. Trees will respawn naturally if away from a base. But wont when nearby. Doesn't matter if the trees were nearby to the base or a foundation or two away. If it is within the nospawn radius re-fertilizer won't work.
Will attach further video evidence onto this post when I return from work.