T-Mobile Galaxy S8's Bixby button remapping disabled
Samsung's latest flagships come with a high price, and the specs and features are supposed to be worth every penny. Sadly, it looks like many people paid for something that is not ready yet, namely Bixby. Even worse, Samsung seems to have something against giving a purpose to a button that would be useless otherwise.
To make a long story short, this is Samsung take on the Bixby button remapping problem - "Bixby has been designed to seamlessly work with our hardware so that you can easily switch from physical to voice control whenever you wish. To provide this ideal experience, the Bixby button will only work with Bixby, so Samsung does not support remapping the Bixby button." This is an excerpt from a longer statement Samsung sent to Android Authority, but it reveals more than enough.
Third party developers allowed Galaxy S8 users to remap the Bixby button for a while now, but those using this flagship on T-Mobile should be careful. The latest OTA for them comes with a trap - once applied, it no longer allows third-party apps to mess with the Bixby button. Even worse, some users also report a few bugs in this update, so if you own a Galaxy S8 on T-Mobile, the best thing to do would be to stay away from this update.