Fuel consumption indicator malfunctioning (--.-)

I have a Toyota aqua and since few weeks, fuel consumption indicator misbehaving. When car is driving in EV, indicator does not show any number. Instead it will show blank (--.-). Like below


But as soon as engine is started, indicator will turn into 99.9 and then gradually starts to calculate consumption and displays my usual consumption (this process will take around 30 seconds to show correct economy). But when car again switched into EV, it will show the same blank (--.-) indication. This happens iteratively.

NOTE: I have replaced 12v battery of my car last week. But this issue was started around a month before replacing the battery.

What should I do to fix this issue? Any help appreciated