Hello Jose,
It seems that this is a bug in MR2012 CU8.
I found some hotfixes related to currency issues on LifeCycle Servcies and a post that reports a similar issue (community.dynamics.com/.../123253). Even though the post is for Dynamics GP, you might face the same error as MR is used for the whole Dynamics AX family.
I suggest that you have a look at the Hotfixes available on LifeCycle Services that might help you fixing your issue.
Probably also an upgrade to a later MR CU might help as your MR is already a bit outdated (CU14 has been released recently).
All the best,
Ludwig