Excel column headers no longer converting since 1 April 2017

I have to convert a PDF file to Excel every week. The format of the source PDF file is the same, but since the beginning of April, every file I'm trying to convert no longer converts the column headers. What change has been made and is there anything that can revert it back to how it was converting the files before? I have even tried converting a file that used to work and it now converts without the column headers. Not happy

I can upload a sample file for testing if necessary.

Cassandra