ADT7470 Hight frequency mode

We are using 3 Fans an 2 Temp. sensors.

We are using this fan controller over 15 years with 3 wire fans in Low frequency mode. (Register 0x40=0xC1).

We started to use 4 wire fans with internal drive circuit, in Hight frequency mode. (Register 0x40=0x81).

The problem is that Status register behavior was changed, in the Hight frequency mode then temperature dropped bellow Tmin and fan controller stops the Fan, but Norm bit doesn't asserted (Register 0x42) only corresponding fan[n] A 1 indicates that Fan [n]  has dropped below min speed

Dump of all registers:

[0x20] = 0x1f
[0x21] = 0x20
[0x22] = 0x00
[0x23] = 0x00
[0x24] = 0x00
[0x25] = 0x00
[0x26] = 0x00
[0x27] = 0x00
[0x28] = 0x00
[0x29] = 0x00
[0x2a] = 0xaf
[0x2b] = 0x05
[0x2c] = 0xff
[0x2d] = 0xff
[0x2e] = 0xff
[0x2f] = 0xff
[0x30] = 0xe7
[0x31] = 0x07
[0x32] = 0xaf
[0x33] = 0xff
[0x34] = 0x00
[0x35] = 0x7c
[0x36] = 0x00
[0x37] = 0x00
[0x38] = 0xff
[0x39] = 0x00
[0x3a] = 0xff
[0x3b] = 0xff
[0x3c] = 0x00
[0x3d] = 0x70
[0x3e] = 0x41
[0x3f] = 0x02
[0x40] = 0x81
[0x41] = 0x80
[0x42] = 0x40
[0x43] = 0x55
[0x44] = 0x1E
[0x45] = 0x7f
[0x46] = 0x1E
[0x47] = 0x7f
[0x48] = 0x81
[0x49] = 0x7f
[0x4a] = 0x81
[0x4b] = 0x7f
[0x4c] = 0x81
[0x4d] = 0x7f
[0x4e] = 0x81
[0x4f] = 0x7f
[0x50] = 0x81
[0x51] = 0x7f
[0x52] = 0x81
[0x53] = 0x7f
[0x54] = 0x81
[0x55] = 0x7f
[0x56] = 0x81
[0x57] = 0x7f
[0x58] = 0xbc
[0x59] = 0x34
[0x5a] = 0xff
[0x5b] = 0xff
[0x5c] = 0xbc
[0x5d] = 0x34
[0x5e] = 0xbc
[0x5f] = 0x34
[0x60] = 0x03
[0x61] = 0x03
[0x62] = 0x00
[0x63] = 0x00
[0x64] = 0x03
[0x65] = 0x03
[0x66] = 0x03
[0x67] = 0x03
[0x68] = 0x80
[0x69] = 0xc0
[0x6a] = 0x7f
[0x6b] = 0x00
[0x6c] = 0x4c
[0x6d] = 0x4c
[0x6e] = 0x19
[0x6f] = 0x00
[0x70] = 0x5a
[0x71] = 0x19
[0x72] = 0x00
[0x73] = 0x00
[0x74] = 0x72
[0x75] = 0x00
[0x76] = 0x00
[0x77] = 0x00
[0x78] = 0x1f
[0x79] = 0x00
[0x7a] = 0x00
[0x7b] = 0x00
[0x7c] = 0x22
[0x7d] = 0x21
[0x7e] = 0x00
[0x7f] = 0x00
[0x80] = 0x00
[0x81] = 0xee