Over a year ago I built an approval flow for News items on our intranet and it has been working fine. It uses a "When an item or a file is modified" trigger on the Site Pages library.
At some point in the last 3 days it has stopped working. There have been no changes to the flow or to the library itself. I've checked everything, even built another flow from scratch. A test flow with the same trigger on other standard document libraries works fine. It seems to be related specifically to Site Pages libraries in all our sites. Has Microsoft changed something?