Has anyone found solution to the goofy RPM readings?

Out of 8 units I have two units reading off the charts... Fans are running normal speed, firmware shows them as launching rockets.

Batch 4 - July 21 Firmware
2640 2400
2640 2340
2880 2580
2820 2400

Batch 5 - July 28 Firmware
2580 2400
5940 7680 <- ?
2880 2820
7620 2580 <- ?