SLA: "MPT Exceeded" after first return from customer status (SM 7.1 SP08)

Hi all.

I've got a very strange error in my Incident Management scenario after upgrading from SP05 to SP08:

1. End-user creates an incident (status New)
2. Processor takes it in process (status In process)
3. Processor sends incident to end-user (status Customer Action, MPT usage calculation stops):

And now end-user returns back the incident to processor (status In Process). Total customer durations are updated, ToDo By date is recalculated with them:

As you can see MPT status is green (and even far from Warning). But if you look at processing log you can see that status MPT Exceeded is set. And it is set by end-user while switching status from Customer Action to In process:

And the status is deleted when:

• processor sets customer status again
• SLA escalation job executes:

I've checked several notes:

Has anybody faced such a problem?

BR,

Artem