I chatted with the Loyalty Manager at lunchtime, who was very helpful with my requests before and during my stay. Seems the cafe Executive Lounge is only open for a few hours in the early evening (Mocktail hour), as I noticed there was no set-up at lunchtime.
Basically for future stayers Movenpick KLIA does not have an Executive Lounge, despite it being listed as having one the ALL website.
Regardless of that, I did like my one night stay here, which included watching landing aircraft whilst working out in the gym.
If they have open the lounge only in time for evening cocktails, then it explains it. But it's a rigid policy. If they don't have open the lounge at regular hours, then free soft drinks/coffee/tea should be provided in the bar/restaurant for guests who have access to the lounge. After all, you have earned this benefit by being a loyal guest.
I have stayed in many hotels with lounge access, different hotel chains, over decades, and always I could go into the lounge for soft drinks/coffee/tea during the day, and some lounges like for example Novotel City Gate in Hong Hong - where I stayed in November, have free flow also of beer the whole day.