Using UltraSigma I can issue this command
* Connected to: USB0::0x1AB1::0x04CE::DS1ZD174801262::INSTR
-> *IDN?
<- (Return Count:56)
RIGOL TECHNOLOGIES,MSO1074Z,DS1ZD174801262,00.04.03.SP2
Using your software, Run command followed by Get Command produces
RIGOL TECHNOLOGIES,MSO1074Z,DS1ZD174801262,00.04.03.SP2
So it seems fine to me but yet when trying to access any feature from the GUI it says can't connect