When I reached MinoLab I was already nearly half-way towards the next level. So I again decided to farm there just until I leveled up, and then push ahead to MinoLord and Megalesios. I found two more pairs of SBC in that half a level so I had no reason to stay and keep farming. I had four pairs of SBC already. But, because I'd decided to stay there until the level-up, I stuck with the plan. And it was on that exact run that I leveled up that the Thorny dropped. So, to put it another way, I'm not having great luck on the "one more run" but rather on each run where I also level up. Weird.
Great to hear that you're able to play again, defboy99.