Hi Isabel:
Thanks for the reply. The guest did write a review at approximately the same time that I did and confirmed this to me. It has been about 10 days since we both wrote our review. I called AirBnB and spoke with a help center representative who told me that she could see both reviews and she read to me the text of my review and the review left by the guest. She could not explain why the reviews were not visible and referred the case to a supervisor. I received a call back 2 days later from the help center again stating that they could not explain why the reviews did not display. As of today, my review does appear on the profile of the guest (which is good) but on my dashboard, the site still tells me that I need to leave a review for this guest and the guest review does not appear on my profile. It appears that this is not only a mystery to me but also to the AirBnB help center.
I think though, that maybe you are correct and the guest review is stuck in posting limbo and might appear after 14 days have passed. I hope that will be the case. Thanks again for your reply.