I am having the same problem with my s8 plus I am looking into starting a class action suit against Samsung because these phones are capable of performing these features but yet they went behind our back and sided with the providers and took the features off. As a customer of Samsung their should be some loyalty to us. I will be working on this and post any information about a class action lawsuit that I get on every Samsung board until this issue is resolved I wanted money on this phone and if I can't use the features on the phone I want my money back.
You do that. Then you will find out it has nothing to do with samsung, samsung provides the apps and hardware that work universally, then the carriers add, change, remove or "fix". Because, unlike apple, Samsung allows carriers to mess around with the programming some negative problems happen, like removing samsung cloud (verizon), or good things like in phone app video messaging. Because tmobile built the programming for their phones to work on their network they are under no obligation to provide a feature that is useable outside of their network or their phones.
Samsung could throw their weight around and force carriers to not change things, but in the US they do not have near the clout that Apple does.
Or, just throwing it out there, again, you could use many of the numerous apps that allow this that are cross carrier, platform, brand and have no fees, like google duo, whatsapp, skype, ect.
Just got the note 10+ unlocked and having the same problem! Had a tmobile note 8 before this and had no idea I would lose this feature!! I tried your steps and got excited until I got to step 5 because that does not exist! There is no option to turn anything on. Would you happen to have an updated solution? Thanks!