Not exactly... :-) You're not right, it is quite different.
I can switch radio from any mode to any mode by Omnirig, only for switching radio from USB DATA to USB I must use some workaround, because if radio is in USB DATA then no commands labeled [pmSSB_U] are executed, ie. no commands labeled [pmSSB_U] are sent to radio. This is the true for UR5EQF logger. Alex's client for Omnirig can switch radio from any mode to any mode. I think Vladimir programmed some internal logic into Omnirig's interface, because this interface knows that radio is in USB mode already and it don't send "the same" message again (USB DATA is in fact USB with DATA flag only). And LSB DATA / LSB is similar.
If I write hexa command for switching radio to USB under any other label then [pmSSB_U] (eg. [pmCW_U]), I can switch radio from USB DATA to USB by pressing CW button.
I do not know how to write more clearly.
You certainly admit that behaviour has nothing to do with something like USB driver.
I closed communication with Alex by now, because Omnirig itself works.
Thank you for your effort to help me.
Mirek OK4FX