I recently ran into this myself, when I was recording my audiobook last weekend. It seems that I use kind of a lot of words that I am not 100% sure how to pronounce. (John Herried called this “Homeschooler’s Syndrome.” Oh lawsy, there she goes again, attacking homeschoolers!!!1!) It happened a few times, but the one I really struggled with was “minutiae.” I asked the producer, and he didn’t know, either. I think I ended up saying “my-NOO-shee-aye.” I did my best to make it sound authoritative.
My kids all learned to read pretty early, and although I flogged them with phonics, they definitely got in some skimming habits. One child who shall remain nameless was recently heard to make reference to “filling a lamp with kernose.” My grandmother told me she once met a guy who thought “fatigued” was pronounced “fatty-gayed.” He’d surely heard the word pronounced, but I guess he just somehow assumed all his life that there were two separate words, which both meant “tired.”
I just love it when little fissures of naivete are introduced into the professional world like this. We’re all faking it, at one level or another.