The easiest thing to do would simply be to set the datahash to NULL on all Inventory Classes in the ResourceUpdateSummary table.
When the server receives inventory from a client, it compares a hash of the data to the hash recorded in the ResourceUpdateSummary table. If the hashes match the server thinks it has recorded the data already and discards the inventory information. By setting the hash in the ResourceUpdateSummary table to NULL, the server will process the inventory information, populate the respective inventory tables and then update the ResourceUpdateSummary table.
UPDATE ResourceUpdateSummary
SET datahash = NULL
WHERE InventoryClassGuid in ( SELECT dc.guid
FROM DataClass dc JOIN vItem vi ON vi.[Guid] = dc.[Guid]
JOIN vProduct vp ON vp.ProductGuid = vi.ProductGuid
where vp.name = 'inventory solution' )
The load on the server will be higher for a while as more processing will be required for the inventory received from the clients, but you will be certain of having all of the various classes populated and up to date.