I use Reading List to mark items to read later. I don't like deleting read items because I do sometimes refer back. In any case, items added to Reading List sync properly across my iCloud devices.
However, I'm finding items are almost always not marked as read on either device when I read an item in the list. I scroll down and read, and get to the end where "UP NEXT" is shown, but hours or days later the item still appears in the Reading List "Unread" section.
Any suggestions on how I can make sure these items are properly marked? Other iCloud features are working reasonably well.