The name First Tick is misleading. It’s actually an anchor location tick must pass. E.g. if axis is from -2.36 to 3.789. Set Anchor Tick as 0 and Increment as 0.5. The major ticks will show at -2, -1.5, -1, … 0, 0.5, 1, …. 2.5
Same for color scale object. By default we only show ticks on major levels. User can set Levels to Custom Levels. And set Anchor Tick as 0 to make sure level 0 shows.