See PR 277492 portmaster may be tainting the MAKEFLAGS or other build environment. refuses to upgrade lang/ghc , but build fine doing build from ports directly. not sure if maybe related to the recent SETENVI changes?
just completed manually updating lang/ghc using ports to build/install and pkg to remove the old before installing the new version
Seems like you found a solution. If this problem occurs again or is still current, please reopen the bug report.