"Can't set parameters. The constraint is broken: MinMailProcessingInterval <= MinMailProcessingIntervalInSync <= ReadyToSwitchHoldingPeriod." constraint is shown when trying to modify MinMailProcessingIntervalInSync value with Set-DMMExProjectOptions cmdl (4263997)

When mailbox synchronization is almost completed, rate of changes in content of mailboxes usually significantly slows down. Therefore, looking for changes by agents as frequent as during the main synchronization phase results in unnecessary load on agent hosts, Exchange server and SQL server. It also slows down the processing of the mailboxes which do have many changes.

Hotfix 20150810EX introduced parameter MinMailProcessingIntervalInSync which is by default set to 180 minutes. That makes MAgE process "ready to switch" mailboxes once in 3 hours and thus such mailbox collections are observed with "Last Processed" values no less than 3 hours. 

Additionally the MAgE log will contain the below message logged fairly often.  It will be very noticeable in Sync only collections where all the mailboxes are in a state of "Ready-To-Switch" and can give the appearance of the agent being stuck in a loop without processing any mailboxes:

All mailboxes have been completely processed or being processed now according to criteria defined by minimum processing intervals for MAgE

If you still want MAGE to process Ready-To-Switch mailboxes more frequently  taking the risk of unnecessary load to agent host, source and target Exchange servers and SQL server you may refer to Adjusting Minimum Processing Intervals for MAgE section in the Migration Manager for Exchange 8.11 – User Guide and decrease MinMailProcessingIntervalInSync parameter value down to, say, 2 minutes.

However, wher running 

Set-DMMExProjectOptions -MinMailProcessingIntervalInSync 2

you get the following:

"Can't set parameters. The constraint is broken: MinMailProcessingInterval <= MinMailProcessingIntervalInSync <= ReadyToSwitchHoldingPeriod.

and the value of the above parameter doesn't actually change.