My S10 had the same problem. I would hear it connect and the drivers showed the phone but Windows could not see it on 2 different computers. I called Tmobile and they told me to look at my notifications and all the way down the list I saw USB Connect and opened it and then clicked on File Transfer and the phone appeared in file manager. What a relief. WHy Samsung maade it so hard to connect the S10 is a mystery. My Note 9 connects perfectly.
Problem solved thanks to Tmobile Tech Support.