Hello @MattBlack welcome to the Local Guide Connect community.
All our posts are checked by filter to detect potential SPAM, false information or not following the guidelines for Google Maps contributions. If only a suspicion comes up, the review or media is not published (“hidden”). Unfortunately, Google never tells us, if that happens and why. In fact, I can see in your profile that 3 of your reviews are indeed hidden.
As a start, I suggest this article How to Get In and Out of Trouble: The Main post .
You can also provide a screenshot of your hidden reviews here. Possibly somebody can give some hints what to avoid.
In addition, I tag @ErmesT because he has much more experience with contributions on Maps than myself.
P.S.
It seems, for your most recent review, you did not wait long enough 
I do see one published 52 minutes ago.