Can't unselect Siemens NX CAM

Greetings,
I am building a post processor with Mastercam as a choice of CAM; when I reach the Post configuration after setting the kinematic, I find Siemens NX selected (not Mastercam anymore) and I cannot unselect it, nor I can delete the Siemens NX node in the Cam Module. I keep receiving a generic Error dialog message either when unselecting Siemens NX or trying to delete the Siemens NX node in the Cam Module:

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Any suggestions on how to remove Siemens NX and leave only Mastercam? Thank you.

Germano Zerbini,
GZ Programming Solutions.