For a few days I've been running a pre-installed macOS 10.12.2 on a new, non-networked MacBook Air with language set to "American English".
I've used "Dictionary" several times without any problems, with the default English "reference sources" (Oxford Dictionary, Thesaurus, Apple Dictionary etc.). The only change to Dictionary I recall making was to activate the Oxford Thesaurus for British English.
My problem showed up when I opened Dictionary today: it would search only in Wikipedia and "TTY Abbreviations" - all other dictionaries disappeared! The "reference sources" list under Preferences now contains only "Wikipedia" and the Turkish dictionary. Restarting macOS did not help.
The problem seems similar to Cannot use Dictionary
except that I still have a
/Library/Dictionaries directory tree:
The problem is also similar to the older Dictionary application doesn't show all the dictionaries I can use, but my Mac runs under Sierra and does not synchronize with any other device. I searched for related macOS bug reports but could not find any.
The problem seems somewhat mysterious since so far I have just installed and used some text editing software on a brand new Mac. Hence it is hard for me to imagine how some preference, plist, files could have become corrupted.
How do I resolve or troubleshoot this?