They come wrong, can't be finished

are you entering numbers then using hints? Hints don't work correctly, if you have any numbers entered in the wrong place, the hints will be based on those wrong numbers. The only effective way I've found to use hints is to use them first, before trying to put in any numbers myself.

If you aren't using hints, I've never come across one that could not be solved.

I only play on hard level, no hints and I check often with the game and by myself. Some games are wrong. Got print-screen for proof.

that sucks. I generally play on hard mode too, only use easy and hints if I'm rushing through Major Drills quests. I have quit an occasional game on hard mode because I made a mistake early on, though sometimes in those cases I just clear it all and restart the same game and it works out. But I haven't played regularly in quite a while, so maybe something has changed.

It doesn't happen often, but yes, it sucks when it does :D Thanks for answering and support <3