Thank you so much, guys! Especially, you Turoskel! <big hug>
I tested and played this challenge with a permanent first quarter moon! That explains it!
You can't believe how relieved I am to find a totally lucid and plausible explanation at last. I feel so much better already.
Edit to add:
I chose a first quarter moon, because ever since the Gnome Challenge, I have the superstitious belief that it promotes multiple adventure holes whilst mining.
@ Turoskel:
I really hated to have to ditch Uni, even if there are an awful lot more seeds to gather. The analyzing tool is such a help. Once you get use to it, it's rather cumbersome to work without it.
Knowing the exact percentage of plants I had to go for proved very useful, though. I could plant whatever and simply note whether this percentage went up or not.
I managed to plant an egg and one cheese from the fridge, but from there on, the omni chain was off-limits for me as well.