Thank you for all your inputs, appreciate it.
@excrab
Thank you for trying but again, off topic. What you explained is quite basically what would happen if you get a shortcut on a STAR, something I'm familiar with already. Look, this is the scenario I am talking about for example: you're 10 miles abeam the runway on a downwind when you do a Direct Intercept course to the FI. In this case, you're on Heading Select and your track is not even intercepting the active flight plan and you're not flying to any waypoint. So, at this point, the descent profile is giving you indications of too high/too low based on how many track miles when you are not really flying on, to, intercepting the active flight plan? Hope this makes my question more clearer.
It is correct, I do work for an airline with manuals at my disposal, thankfully. And while I also have other people who I could ask, I do consider PPRUNE as a valuable resource since there are too many colleagues here with far more experience than I have and I see no shame in asking them. And my ego does allow me to learn from someone with less experience or even not a pilot AS LONG AS he/she is able to provide a reference for what they say, something repeatedly asked for.