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

So on Friday I was on a screen share with someone who was having this issue. Same as before, with styles defined as "+Body", Body defined as Aptos, but the text showing up in the font dialog as "Times New Roman (Body)" which is obviously incorrect. Well, it correctly showed that it was displaying as Times New Roman however that definitely wasn't the Body font.  

As a test we tried picking some other font schemes, but the text continued to display as TNR.

Finally I thought we should try clearing the cache, so went to Options > Save, checked the tick box to remove cached files when Word closes (which really should be on by default, it causes no end of trouble when you're working with SharePoint!) and also clicked the button to delete all cached files. Once that was completed we closed Word, and upon re-opening all displayed OK.

Whether this has fixed it completely I can't say, but writing that up here in case it helps anyone.