Google does some shadow filtering on their end. I had the same happen to a 1-star review - it showed fine to me when I was logged in but wouldn't show when searching for the business using an incognito tab in another browser. Had I not checked I would never have known that the review was invisible. The logged-in view faked the number of reviews (one higher than the incognito view), the aggregate score (0.1 lower) and showed my review in the info card.
The reason I suspect it's something automatic (at least in my case), and not something targeted by the business I was reviewing, is that I removed half of the review and it did start showing after around 10 minutes of waiting. I edited the removed half back in and it vanished again. I was eventually able to narrow it down to a couple of paragraphs. One of them contained swearing ("fucking" and "assholes", which the management of the business were), which I guess makes sense. The other was very innocuous so I have no idea why Google disliked it. Anyway, by that time I'd gotten bored of having to wait ~10 mins after every step of this bizarro dystopian binary search so I left it at that.
At this point it's received a handful of likes, and I received an email notification that a hundred people have seen it (and that I should register as a "local reviewer", yeah right). So I guess it's going to stay up for good now and don't need to check it daily out of paranoia any more.
And yes, this was the first and only review I've ever written on Google, in case that's part of the equation.
My biggest takeaways from this were that a) holy shit Google employees are a bunch of assholes and can go fuck themselves for writing code that shadow-filters a review instead of giving any indication that it violates their puritanical Christian policies, and b) Google is apparently not smart enough to fool me when I searched for the review from an incognito tab in a different browser but the same client IP, which almost seems like a mistake. Like, if you're going to make the effort to shadow-ban people, why not be thorough about it?