Recently I am having an issue at work where users cannot search for PDF's added from January of this year and on. I have all the folders indexed, I have tried installing the File Indexing and the Windows Search server roles and I have checked that the correct iFilters are installed. I have also rebuilt the index, twice. We are able to search for files in a folder titled 2015 but nothing in 2016 shows up. Some files in 2015 are added from this year and they can be searched.
Any ideas as to what could be causing it?
EDIT: I am searching by partial file name, i.e. 567 in 123-4-567-890