Box Characters in Doc Extraction AI Skills

I have a use case for AI Skills but it seems whenever i pass any document this happens. For this example im passing a PDF file exported from a word file uploaded to appian, and it is being called by the process model below as a constant. 

Using the Extract From Document Smart Service doesnt give me an output, when I check the reconciliation all characters are being outputed as boxes, as shown in the screenshot.
Checking with the actual document before and after goes through the smart service ( document passed through different variables for before and after ) and it is shown normally. 

Would want to understand why this is happening and what steps i need to take to rectify this issue.