Hey there, Jack. Thanks. How do you recommend I upload the save? I stripped all my other mods and tested again and it's just Only Gleba, and On Wayward Seas (however it also adds Dredgeworks and Dredgeworks graphics). Of course the other items on there are the standard Factorio addons like Space Age and Quality, etc. I also did a test only disabling your mod and I am able to plant on Gleba, tested through the scenario editor.
Edit: I should mention specifically, it's just the sunnycomb, cuttlepop and watercane (wood) that have the issues. The other plants are fine.