Why isn’t the unit being discovered by VSA software hosted inside the instrument itself?

If the analyzer is reporting Keysight Technologies as part of the *IDN query, the VSA does not recognize this response as a valid instrument that it can use until VSA version 18.7.

If the same VSA version needs to stay, the *IDN response of the MXA can be changed by pressing System, IO Config, System IDN Response, Keysight.