Use a text PDF, not a scanned image
If you printed your resume to PDF from Word or Pages, that is a text PDF. If you scanned it, that is an image. Image PDFs do not extract.
Try paste-as-text
If the PDF will not parse, copy the text and paste it into the resume import text box. Plain text always works.
Keep file size reasonable
Under 5MB is safe. Above that, compress or save as a smaller PDF first.
Avoid very columnar templates
Two-column resumes can scramble in extraction. Try a single-column version for the upload, then keep your visual one separately.