PX4 VTOL Config Motor & GPS Problem

Hello i have Vtol 4 +1 quadmotor design and i use holybro pixhawk 4. I tested 4 motor with using px4 basic frimware and using basicquadcopter autonomus flight is okay. After that i want to use vtol in basic mode motor is not foundjust 8 motors bar and if i change frimware to master mode i can config to our system easily instead but i had this error message “GPS Speed Accuracy too low”. When I go back to basic software immediately after getting this error, I don’t get any errors. What is the reason? If I have a chance to install vtol engines in Basic mode, I can fly in that mode, but I can’t choose the engines, I’m stuck between two problems. Could you help?

What do you mean with Basic Mode? And which PX4 version are you using?