I am not sure about Epic Architect, it's been a long time since I've used it. However, in Epic Editor, compiling your doctype does not create a .GRP file. Compiling the *FOSI*, however, does create the .GRP file.
If you are able to use Format > "Modify Element in Context", place your cursor inside of an element that has an e-i-c and select Format > Modify Element in Context . In the subusequent FOSI panel, click in one of the fields that has content, so that the left-and right-pointing bold triangles appear. Then hit return. (You don't have to actually change anything.)
Then go to the Apply menu of the FOSI panel and select Apply Format Changes. (This selection should now be available, whereas prior to performing the above paragraph, it was grayed out.) You should shortly get a message from Epic stating that the FOSI has been successfully compiled. You should now have a .GRP file.
There is probably a way to do this from the command line, but I don't know what it is.