I was playing around with Supradoku and f-solver and created a puzzle that has a unique solution according to supradoku, but f-solver is unable to find it (on my computer, at least). I tried to solve it by hand, but quickly found that I needed to use a lot of bifurcation. I wouldn't be surprised if some sort of set equivalence or other advanced techniques can make it more manageable, though.
Rules are standard anti-knight and thermometer rules, so squares that are a knight's move away from each other cannot hold the same digit, and digits on thermometers must increase from the bulb. you can try it at https://f-puzzles.com/?id=y9xokmpg
Since I was having so much difficulty, I looked at Supradoku's given solution, then saw a couple places I could add thermometers to make a much more manageable puzzle (with the same solution). In my own testing, this version took me about an hour to solve and was very enjoyable.
You can play the easier version at https://f-puzzles.com/?id=y96q9yxy