A lot of ticket stations I have used will fail on chip and signature (e.g., Arlanda Express/train stations in Sweden, train stations in Amsterdam), though others work fine (e.g., London Underground).

I've also had some weird behavior occasionally with credit machines where chip and signature will be declined and if I ask them to swipe the machine will require the chip to be used. I carry a non-chip no FTF card specifically to use to swipe in these situations.