Sony Xperia Z1s (C6916) T-Mobile owners have yet to see Lollipop roll out. Recently, Lollipop firmware update 14.5.B.0.220 was certified by the PTCRB and now a newer update has been certified with build number 14.5.B.0.228. Hopefully it won’t be too long before it is released.
Thanks difwwh and WilliamTell!