"Heading" and "Body" fonts are sometimes incorrectly displaying as Times New Roman

This appears to have started with the latest update that also made table formatting go nuts. Sometimes when we open a document from SharePoint, any text that has been formatted with "Body" or "Headings" will display as TNR. The font box will show "Times New Roman (Body)". The style definition will show "Body". Under the Design tab, the font scheme shows the Heading and Body as both being "Aptos" though, which is correct.

Limited testing shows that closing Word down completely fixes it. But it's causing a lot of consternation!