There's quite a bit of B71 only in Northern WI, but it seems based on the TM MVNO map where you can see what LTE bands are available in a spot, B71 deployment has definitely stalled. Madison and Milwaukee are not good markets for TM, I know largely because spectrum availability is so low. Sprint isn't great in WI, but TM is even worse, especially rural. I hope they have a commitment to make it better.
The map I'm taking about: https://maps.t-mobile.com/pcc.html?map=mvno-noroam-34l
I hope TM is also committed to combining their B2 and Sprint B25 ASAP.