Node titles are erased when I update a field with entity_metadata_wrapper
I tried calling resetCache but the problem persisted. In the end I created a page for each language and used the PHP filter to add the script to the page. By switching to each language, setting the value of propertyCondition('language','') to the loaded language and loading the corresponding page, I was able to import the metroIDs and update the pages, one language at a time, without deleting the titles.