The T-Mobile LG Stylo 2 Plus (LG K550) today received the K55010p Software Update. The LGK550BNGO1 model variant received the K55011p software Update.
According to LG Open source website, This is still the Android 6.0 M software update which brings the January 12, 2017 security patch.
The update is available now via FOTA and LG bridge, if you want to manually install the update with LG UP, You can download the stock kdz firmware for LG K550 from below links:
Download T-mobile LG Stylo 2 Plus K550 Stock firmware
Model: LG K550BN
Because LG has made some changes in its server settings, You can not use browser to download the firmware from above links. You need to use XDM download manager or other download tool to download kdz file from LG server. Learn how to download LG frimware, Check this guide.
Remember to bookmark this page – Download LG Official Stock ROM / Firmware [U.S.] -Where you can track the software history for the Lg stylo 2 plus phone from T-mobile (K550) and MetroPCS (MS550).