Welcome back! Unfortunately I’m having trouble adding captions to images. Here’s the response from WordPress when I raised the problem.
“…this is an issue with some older themes interacting with our new editor software. The caption text is white in the editor, so it’s only visible if you highlight it. I would recommend looking into activating a newer theme when you have a chance, as the theme you’re using is about 10 years old and will eventually not be updated. Our team is aware of this bug though and working to resolve it for all themes, I just don’t have an ETA for when that might happen.”WordPress.com Chat
I’ve tried out a couple of new themes for the blog but the caption problem is still there, so I’ve reverted back to my regular theme and hope WordPress can resolve the problem quickly. In the meantime, I’ll devise some kind of workaround for captions when I post again later this evening.