High, crossfire rx loss

fly high over 1100m - crossfire get the “rx loss“, but not failsaved... setup: frame iflight XL5 V3 true X, fc airbot omnibus f4V6, esc 4 in 1 airbot furling32, fpv cam foxeer predator 4 mini, vtx akk Х2P 800mwt, foxeer lollipop3, receiver crossfire nano immortal T, motor Xing 2207 2750kv, props HQ V1S, betaflight rpm, gps beitian-220, accum 4S CNHL Black 1500mah 100c, app Xlite pro(crossfire micro) stock antenna, googles skyzone sky03new. HD cam Runcam5 orange