Thank you all. Of course, I understand that original is always best.

The original resident permit is not physically unique. The original is a b&w computer A4 printed paper with a 1 inch round purple symbol and signature stamp. It is not anything other than a plain piece of A4 paper.
The original has a b&w photo of me on it. All the numbers on my multi entry visa match the numbers on the resident permit. The stamped signature matches in both permit and visa. The only thing different was that I had a b&w round stamp and signature, instead of purple.
In the 14 months I've had the permit and traveled almost monthly overseas, this was the very first time I've ever been asked for it at departure from a foreign airport. I am now aware that timatic does mention the supporting document. I have always shown the resident permit (copy) at both departure and arrival in India, along with my passport and visa but never previously at a foreign country departure.

What is frustrating is that if I did not need the lounge pass, I could have gone straight to the gate with my phone boarding pass. I was already checked in.