Can the airspeed be marked negative?

Today I flew my first vtol flight (1.10.1)
Although it is not a vertical technology airplane, it has the same shape, so I chose vertic technology and activated airspeed.
I was very surprised just before the transition from multicopter to fixed wing.
The airspeed was momentarily marked negative.
Surprised, switched from multi-copter status to manual landing.
I was very embarrassed because I had never experienced it in 1.8.2 on the same plane.
I wonder why it’s marked negative. I ask for any help.

(1.8.2 is confident that it is not a hardware problem because it is possible to fly without any problems.)