Ohm symbol appears in PDF viewed in browser, missing when viewed in Acrobat

I've created a PDF using AEM Guides (via DITA-OT 1.23). The PDF contains several ohm symbols. When viewed in the PDF in a browser (selecting the PDF from the Generated Output area in AEM), the symbol appears correctly. When I download the PDF to my local system and view it in Acrobat DC or Reader, the ohm symbol disappears (blank space instead). Any help/tips is greatly appreciated!