Very odd FCX issue

[TankII]

We have no problems with FCX-648S (ADV) units connecting via 10 Gb fiber MRP to our TurboIrons.  However, we have some FCX-648 units that will not connect at all.  Neither trunked, single-leg, or MRP.  Doesn't matter if they have S or R code, and the version is the same as on our very smooth running 648S versions.
The 648S versions are running XFP's while the non 'S' version are running SFP+ interfaces (Same part number as the TI's).

I posted this question on Brocade's forums, no answers.
http://community.brocade.com/t5/Ethernet-Switches-Routers/FCX-MRP-issue-Model-specific/td-p/88192

Checking in here for help!  I have two switches that are essentially useless outside of L-3 lab environments.
:-(

TankII

[Airuei]

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