Trying to understand my wife and fantasies.

Background- we’re both around 50, with a very active and orgasmic sex life. We are both exceptionally happy that way.
A few years ago, we were both getting bored and started swinging 2-3x per year. It reignited us on many levels. Things got more creative again, etc etc. We also appreciated each other on a new level and are more open and honest with each other than most married couples could even fathom.

The question- I am very much invested in fulfilling my wife’s fantasies. As you might guess, the sky is the limit there, and we have access to other partners for this as well.
I’d have to imagine that most wives being handed this freedom, having already done plenty right in front of their husband while he cheers her on, or he joins in, or he is busy doing his own thing with the other wife… that there would be no hesitation to rattle off her fantasies when asked.
- under a waterfall.
- 3 guys at once.
- bondage.
- etc.

Nothing. I get nothing back when I ask. She is a very frank person, so I generally just take her at her word. But when she says “I don’t have sexual fantasies” I must admit I just don’t buy it.
She’s repeated this. She’s also said “I get shy with that”. To me, those two things don’t line up.

Am I reading into this too much? Is she just not comfortable saying stuff out loud? Or is it true that some people don’t have naughty fantasies? I’m very much confused and incredulous.
Who on earth has zero sexual fantasies??

Help me out here. I don’t get it.
(Not looking for explicit stuff, just trying to understand her better).