I have a comparable problem. When I update the Participants db by a script that runs outside of the Participantsdb plugin, in many cases I have to wait 24 hours before the results are visible via the plugin. I have seen that the plugin has its own cache that is by default set to a DAY (in the PDb_Participant_Cache class). In the Settings of the plugin there is no way to clear this cache or to set its expiration time. This would be a very helpful feature.
Thomas
