Could you please confirm which application you used for making interactive PDF?
Most likely the problem is due to the PDF file being created by Microsoft's own Save as PDF functionality which doesn't properly handle any OpenType CFF fonts (i.e., fonts with the .otf suffix and that have CFF outlines). The text is simply put into the PDF file as low resolution raster images; that is why you cannot select, copy, and/or search such text. (Microsoft is aware of this shortcoming but has refused to fix it for many years!)
The workaround is to license Adobe Acrobat and use the Save as Adobe PDF PDFMaker functionality that Acrobat adds to the Microsoft Office applications.