I know these days we're encouraged to think in terms of ranges instead of putting opponents on specific hand/specific 2 hole cards. But a big part of why I play poker is cos I like to figure out exactly what cards they have.

When I'm not involved in the hand, I can figure it right by the river often enough (not really as often as I'd like). When I'm in the hand, however, I find that I more preoccupied with thinking about what my action should be and not trying to put them on a hand so much. Even when I do think about it and try to put them on a hand, I think I get it right less often than when not in the hand.

Any suggestion/tip/thought process to follow to combat this?

You answered your own question in the first sentence, work on figuring out ranges instead of essentially just guessing what hand they might have based on what hands can beat you. How are you figuring out what actions to take without taking their range into account?

When one studies hands, one does creative thinking and it takes time. I think only the GTO then. When I play, I am aware of the stats of the opponent and I feel the opponent and the situation. When playing, one thinks fast, using only whatever one knows, not more.

It is important to think about the opponent's range, so one can figure if one has what it takes to do this or that (bet, call, raise, bluff, size). One is like never against just one possible hand and it is vital to have an idea if not the exact calculation of the combos he will hold in some situation.