I have noticed the volumes created by simple volume create from the ontap cli are not visible immediately, or even after 'couple of minutes' within the corresponding FSx/AWS console (GUI). Not even after numerous refreshes, and/or navigating up and down the filesystem/volume/svm hierarchy...
On the other hand, volumes created from the FSx console are visible immediately by the very same ontap cli console volume show...
I can understand minor delays but my anecdotal evidence is more like 'couple of minutes' where 'couple' may as well be 5 mins or so... Also, the failure to show after 'refresh' does not look good...