engine does not shutoff with replacement hv battery

I put a 6 month old almost new hv battery in my 2005 Prius to replace the original that was faulting. It drives nicely, with no faults, but I noticed the IC engine never turns off, even at stop signs. The MFD display is indicating the engine is off when the engine is running while motionless at a stop sign. I noticed the charge indicator was showing an almost full charge with several green bars and one blank bar at the top, but the engine still ran while the car was stopped, apparently still trying to charge the battery. I used the battery ecu that came with the replacement battery.

What do I need to do to eliminate this problem and get the engine turning off when the car is stopped?

I only drove it for 20 minutes after installing the almost new hv bat. Do I need to drive it longer to let the car fully charge the hv battery? The replacement hv battery had not been driven for 3 months.

Do I need to swap ecus and use the one from my original battery?

I did search the forum for a prior answer but did not find one.

Thanks for your help,

Doug