Since the implementation of the new discovery format, I keep getting smart matches in the list that when Review is selected, the page shows an empty result with the message "no matches...", It begins with one and is now up to six matches with no data.
Sorry for delay. There is a small footnote to the waiting queue. If Your tree is somewhere in this queue and You change something in Your tree, the tree will move to the end of this queue. Repeated changes will have repetitive the same effect and at worst the tree will move at the end, over and over.
This is one 'bad' condition that can happen. So, You can try to stop changes in Your tree for a couple of days. If it doesn't help, I can drop an email to the support. So, feedback is very welcome.