[2019] I seem to not be able to plant a 4th spirit tree. what am I doing wrong?

Can you send me your RSN and i'll give this a look? Can't see anything immediately noticeable from your images.

Looks like you've done the "Family Spirit Tree" achievement but not actually "done" it - which can be done just by speaking to Glouron to finish it off haha. Glouron can be found by the Prifddinas Spirit Tree in Cryws. You'll then be able to plant the Spirit Tree :)