First: make sure you have the latest firmware installed.
To hear the effect of the SEQ MOD in the MOD Matrix, you should use different values for the steps. The value of the individual steps is set by holding the step button on the SEQ page while turning the MOD value knob.
In you example, you should try: first step with MOD value +99, next value 00, next value -99 and so on.
Then you go to the MOD Matrix and you select the destination (in your case VCO1 pitch) and set the modulation depth.
In other words: on the SEQ page you set the values for the steps and on the MOD page you set the destination and the modulation depth.