Literal text strings in the visualizer inside the autoexp.dat file do not allow the use of a colon. This generates an error in the autoexp.dat file. Changing the colon to another character works as expected.

Example class:

class test
{
public:
    int hour;
    int minute;
    int second;
};

autoexp.dat entry:

test{
    preview
    (
        #( $c.hour, ":", $c.minute, ":", $c.second )
    )
}