Today I get rid of the compression Profile defined in the Virtaul server corresponding to OWA services and works like a charm.
For some reason, when EV XML traffic gets compressed by LTM, it adds/modify some XML information and that's what causes all the problem.
We're monitoring services in order to validate if things are still going well. If so, then i'll modify compression profile and suppress every entry corresponding to XML:
application/(xml|x-javascript|javascript|x-ecmascript|ecmascript)
thus letting other objects to be compressed.
Hopes this late advice helps.
Regards.
hheredia