Adobe InDesign v17.0.1
2020 Mac Mini, Apple M1 chip, 16 GB memory
macOS: Big Sur, V11.5.2

I have a multipage document with a folio and page number in the footer. The footer text is a regular weight Helvetica Neue LT Std (OT) font, and the folios (page numbers) are bold; the bold is nested into the paragraph style for the footers with a GREP designation. The footer text boxes are NOT active on the pages but are linked to the parent pages. Expected result: all footers match the font weight of the footer in the parent page to which they’re linked, defined by the paragraph style.

Actual result: Sporadically and haphazardly, the entire footer on one page will be bold; this appears, disappears, and reappears while scrolling through the document. I closed the document, quit InDesign, and reopened the document, and found that the issue appeared on a different page. The problem is that it's also showing up when exporting a PDF. This is a big issue, because I don't want this printing—and never know where it will show up.