Thanks for the reply David.

We’ve checked the objects and all formatting was applied using object styles. I’ve even gone so far as creating a test object style that only has the paragraph style attribute activated. I then created two different paragraph styles, applied the object style to the object using the first paragraph style, exported the snippet, change the object style to use the second paragraph style, placed the snippet (both dragging it into the document as well as using the file>place command), but the first paragraph style remained, with the object style showing the ‘+’ indicating an override.

I’m currently using InDesign CC 2013, so I’m not sure if the behaviour has been changed between this and the 2014 version.