@AdryasG I have a couple of tips for getting more harvestables that you could try if the plant is on your home lot and if you haven't already tried these yourself. I do find that this particular plant doesn't produce that many harvestables but unsure if that's a bug or not.
Firstly you could put it indoors if you haven't already, sheltered plants can keep producing harvestables a little better than outdoor plants in my experience. I put all my rare plants indoors in my garden centres or for my specialty gardeners including the intergalactic growth pod. You could put some indoors and leave some outdoors to see if there's a difference.
The other tip is to wait until the plant bears harvestables in the morning at after 5am, so slow down the speed if your Sim is sleeping about that time then quickly go into build mode when the plants produce harvestables, take the plant into your household inventory then put it back again and the harvestables will appear in the inventory. Repeat this as the plant continues to produce harvestables until it stops at around 6am. Your household inventory should then have many more harvestables in it than it would have if harvested by your Sim. It will also help you check how many harvestables are actually being produced by each plant. That way you can see if there's a bug with moving harvestables into the personal inventory, or if some plants aren't bearing enough in the first place.
I'd also maybe test other regular plants alongside alien plants to see if there are issues with any of them too if you haven't already done so. Maybe try some wild plants too and see if their harvestables go into your inventory okay.
Could you also tell us if you are on console or if you're on PC with mods? Knowing that can help to find assistance from the right place. I'm on Xbox Series X.
