Unable to search within PDF text boxes in Outlook 2016

We have noticed that since upgrading the Office 2016, that Outlook can no longer search within text boxes located within a PDF. We have the 64-bit ifilter installed, but the only fixed searching the PDF and did nothing to fix within the text boxes. We have some PDF fillable forms that get emailed to people and they are unable to search for data within the fillable text boxes. Has anyone run into this and been able to correct this issue?