I have X-Plane 12.08rc3 with the RXP GTN 650 and GTN 750 installed. RXP GTN version 2.6.1.1 (update info shows 2.6.1.0 but I installed 2.6.1.1 ...). On RNAV approaches with vertical guidance (LPV, LNAV/VNAV etc) the aircraft HSI shows "NO GP" and vertical DI info is not shown. Problem demonstrated with the LR Baron 58 + GTN 750 and LR Cessna 172 G1000 + GTN 650. Laminar Research tells me the issue is 12.08 introduced a new dataref: sim/cockpit/radios/glideslope_signal_valid[4], which needs to be set to 1 for GPS approaches with vertical guidance. I verified this with a LUA script. I hope RXP can provide a fix in an upcoming release.