There isn't any input via USB DJM250 for CH2

Windows 10 connected via USB to DJM250. Rekordbox and driver intstalled. There isn't int any input for CH2.

Preferences setting in Rekordbox for input CH1 USB 1/2; CH2 USB 3/4

CH1 and CH2 have been set for USB source in DJM250.

Why there isn't any input for CH2?

There isn't any issue if I select line for CH2.