Loss of Graphics Data in PDF Files Linked to SharePoint

I created a report in PowerPoint with a Gradient background that I turned into a PDF. We recently synced the PDF file location to our SharePoint site which creates a thumbnail that matches the cover page of the PDF. However when I view this in SharePoint viewer, the gradient is altered to a big grey arc on the file as if there was some data loss in syncing.  If I select "Open in Browser" the gradient is correct, BUT it is darker than the original file.  The only way I get the true representation (how it looks in PowerPoint and the original PDF), is if I force open in Acrobat after I went through the initial step of opening in browser.

TLDR: I need to maintain a PDF for this file, so my question is: Are there options when setting up SharePoint to force open to a PDF viewer - or - is this an issue of compatibility between PDF files and Microsoft SharePoint? 

I noted previous compatibility problems in the past on Google search, but nothing too recent or that solves the issue of graphics not rendering as they should?