\startembarrassment I found out what caused the strange behavior. I was testing the font in a directory where there was also an old instance of the .tfm-file. So Context would search the working directory, find everything it needed to produce the font, and thus neglect all the new stuff I had modified and installed into $home/texmf. Performing the tests in a different directory removed all the unexplicable behavior. \stopembarrassment Thanks to all for looking into this, and sorry for the confusion I created. On an unrelated note: please forgive if I seem sluggish in responding to posts. For some reason I can't figure out (and Erik looked into this and tried to help), some of my posts take three days or even longer before they get posted.