There are a few things you can do to improve the success and the number of suggestions you’re seeing with batch tagging. All the options mentioned can be found in the Advanced section of the Settings. You can access them by going to the More Menu (the three dots in the top-right) -> Settings -> Advanced
Turn off Auto-Tagging so that all instances of faces must be confirmed. When tags are confirmed, the accuracy of the face identification can improve.
Move the Face Recognition Proposals slider to be a bit less accurate. The default is 80, play with it down to 70 or 60 and see if that returns more results.
Merge Small Batches (toggle the option on)
Adjust the minimum Batch size
You can learn more about these setting and about Face Tagging in general in our Manual HERE