Which post is the latest one that was successfully received by your subscribers ?
Have you asked any of the subscribers to check their spam folders for the two recent posts ?
There's a relatively obvious problem with the post /2017/03/march-2017-meander-falls.html :
the first image (the map) is not uploaded normally, but is embedded as base64 data.
Did you drag&drop it to the post ?
Anyone viewing the post itself will have to load ~1640 KiB of HTML, and add to that the
several normally uploaded images.
In the feed, the map image is taking up ~260 KiB of space. Many services ignore or can't
handle a post in a feed that is larger than 100 KiB.