Strange behavior in exposing in/outputs of a VST to a DAW

I’m working on a VST (2) plugin from which I want to expose a number of in- and outputs to the host DAW, in particularly Ableton Live 9.6.2 but I’m not quite understanding what triggers the DAW to find the in and outputs. I use the Projucer to set the configuration item Plugin Channel Configurations.

I understand that channels 0 and 1 are used as track inputs and track outputs in Ableton Live. What I want to do is expose the other in and outputs as demonstrated in these two images:

This occurs if I, via Plugin Channel Configurations, set number of inputs or outputs greater than or equal to 9 (e.g. {9, 9}). This makes three inputs (2/3, 4/5 and 6/7) as well as four outputs (2, 4, 6, 8) available. If I set inputs lower than 9, all the inputs disappear, and conversely if I set outputs less than 9, all outputs disappear.

Using this feels hacky and unsafe, and I’d like to understand what causes this and how I can configure this myself. I only care about Ableton Live 9.6.2 currently.