Have you enabled any filters in the Hud > Edit Hud Options > General?
By default the Hud will show lifetime stats for all opponents - you have to enable session stats manually in the Hud, and they will be shown in red if you've done that.
If you don't think any of your Hud options would be hiding any opponent stats please open a Support Ticket
and report your problem
. Attach screenshots along with your log files and give us a specific example of an opponent who you have more hands on than are being shown in your stats.