XUAV-Talon 1718 Wing span VTOL Conversion _Error

Hello All ,I am in Process of converting, a Xuav-Talon to a VTOL setup, , I did some flights today and have an transition flight as well, everything looks good , i feel system is on heavy side, using with Lipo 6s 16000mah, attaching the log for reference, i keep getting Error compass variance during the flight, i suspect some interference inside but any other inputs on the system will be useful for me to fine tune the system.
System Setup
Extended wings to Hold Carbon Rods for VTOl motors
Quad Motors -5820 330KV-15 Inch cf prop-40Amp Esc
Fixed wing Motor - AT4120-Kv500-15*8 Prop - 80 Amp Esc
Will upload log via google drive
Test Flight Video