Ideas
I encountered the same issue on the Mac version. I did some investigation into this bug, and it seems that after summoning Spruce Almighty and then playing another household living in Sprucederry Grove, once I accepted and completed the fable quest from Todd, I was no longer able to summon it again.
The way I managed to work around this bug was by summoning Spruce Almighty from another Glaswood Tree that I placed in the Sprucederry Grove lot using the cheat code “bb.ignoregameplayunlocksentitlement”. After some time passed and he returned to the tree, I was able to summon him again from both trees.
The steps I described above are just one example of how the bug can occur and how it can be resolved — there may be other ways as well.
(These sentences were translated with the help of ChatGPT. I apologize if they are somewhat difficult to read.)