The theme does not contain anything that will make an image description either appear or disappear.
When you say “descriptions of my images” are you referring to each images ‘Caption’?
Also when you say they “used to show”, what changes did you make from previous to now.
Did you change the theme?
Make changes to your permalinks?
Add/remove or update any plugins?
Any other changes?
I notice that on the pages you posted, some images are being loaded internally from your site, and some are hosted on wp.com. Are you using wordpress.com hosting and/or Jetpack? If so, it would be worth asking the support of those services as I don’t think it is a theme issue.