Spotlight doesn't index .docx Microsoft Word files

This is a reply to the old thread Old problem with Spotlight and Word .docx files

I noticed that docx files are not indexed (High Sierra 10.13.4). This is a huge problem for me, and a nasty one as it's not easy to discover.

From what I read in this thread and elsewhere I understood that the problem is that /Library/Spotlight/Microsoft Office.mdimporter is used to index docx files, which it doesn’t properly handle. Removing the importer fixes the problem, but breaks old Word (.doc) and Excel file indexing. Explicitly calling mdimport also does, but has to be done each time file is modified. I am not sure how Spotlight decides, which importer to use to handle specific file types, but in the info.plist for the misbehaving Microsoft mdimporter I found a mention of docx. I made a backup copy of the Info.plist, removed the array element describing docx (<dict>…</dict>) and saved. However, newly created or edited docx files were still not searchable by spotlight. I wasn’t sure the changes I made were noticed by spotlight, so I rebooted my Mac, still the same. Finally I changed the modification date on the mdimporter (touch /Library/Spotlight/Microsoft\ Office.mdimporter). After this the docx files I create and modify are promptly indexed automatically. I am not sure whether this solution will last and if it will survive software updates.