Does anyone know why https://phabricator.wikimedia.org/T264505 would be happening?
Topic on Project:Support desk
your eval.php example is probably not working because mw isnt initialized properly there. Its probably isn't related to your actual issue.
If i were to guess, something wrong with localization cache. Check mw debug log for errors related to it.
Thanks, just realized there was a response now. The localisation cache has been rebuilt and I haven't seen any errors relating to this.