am also facing the same issue
agent installed sucessfully and then secure agent is also done
when i ask for the status it says the last upload is 0 with pending files like 300 etc xml files
as when checked in the emdproperties directories there were 0 files
Sometimes it isn't the obvious locations either. I recently had a case on a 10.x database where the UDUMP directory had filled, and that caused the collection to stop. Once I cleared the space, the agent resumed monitoring.