Yes, you have to be in Preset Mode to use the footswitches to scroll through the presets. The Preset/Play Mode only refers to the functionality of the footswitches and does not depend on what preset or group of presets you are currently on. The way to toggle b/t the Preset or Play mode is to PRESS AND HOLD the right footswitch (you can also do this via MIDI, or with an AUX switch).
In Preset Mode the middle and right footswitches scroll down and up, respectively, through the presets, and the left footswitch loads a new preset or does active/bypass. In Play Mode, the left footswitch does active/bypass, the middle footswitch is the programmable HotSwitch, and the right footswitch is Tap Tempo.
We highlight the first 12 presets because they contain (by name) the algorithms (signal processing constructs) in the box. Every other preset in Space is built from one of these first 12. But again, they don't have anything to do with Preset or Play mode, which only applies to footswitch operation.