We agree to disagree. As I read your screenshot (I have several similar ones), it has dropped into CDMA 1x800 - NOT LTE 800 -band 26.
There is LTE somewhere which is seen by the M9, but not where it counts. LTE in this case is treated as a neighbor and not as a functional frequency. At least that is how my HTC One m9 performs.
Good folks here persuaded me to go tri-band. I picked up the M9 based on that, the good name of HTC and the deal Sprint gave me with the m9 device.
I often dream of going back to my Motorola Photon Q which on a day to day functional basis was far more dependable than my experience with the M9.