I’ve got a feeling this might be to do with one of the content protection plugins you are running on your website. Could you try de-activating them and seeing if that fixes things. Whilst testing i would also clear the cache and de-activate your cache plugin,
De-activating the content protection plugin did the trick. Thanks! Thanks also for – once again – reminding me to clear the cache, too. Some day I may actually remember to do that before I look for other solutions.