You can monitor from the heavy forwarder side, as well as from the management server. In my case, I have a heavy forwarder on Red Hat, and a secondary management server that I'm connecting to for log retrieval.
I open a screen session, and split the view into 2 panes.
On the HF:
watch -n 1 "ps aux | grep -i opsec"
On the management server:
watch -n 1 "ps aux | grep -i lea"
From there I can see the number of lealoggrabber sessions running from the HF, and the number of leasession instances on the Check Point box.
On a related note, I'm also having trouble retrieving data. It seems to circle around pulling SmartDefense data, or if I use the Non-Audit setting (which also includes SmartDefense).
I'm still testing, but have found that I need to disable all inputs on the HF, restart the splunk process and reboot the management server to get to a clean state to work from.