Simmingal - I tried replying to you the other day. I had typed my reply and decided to insert an emoji. I selected the emoji button and my screen went blank and my message was lost.
I did try the work around you suggested but it has not worked. I just checked the post in the migrated thread which I was trying to edit. The image is visible in the edit mode. However, none of my changes take effect after selecting reply. As well, the link for the text is visible, which I had deleted, and the photo does not show. I have found a feedback post that users were having problems with migrated photos.