It's a bit more than one or two specializations on high collab if not made even harder, but yes thats the general rule of thumb.
The commands above should fix this. The yield layers are generated from the nutrient layers. If there is no yield layers for plants then nowhere on the world map there is a nutrient span that works for these plants. You need to wait a bit after using the command, it will slowly fill the layers.
If this still doesn't fix it, a screenshot of the yield layers and a screenshot of the nutrient layers at the same areas would be helpful to investigate this further.