I have a similar problem. It’s not any of the plugins causing the issue and I really don’t want to go through the hassle of switching out my theme. What happens is I upload the pictures and they all say “There was an error uploading the file. Please try again later”. But then if I change the option from showing All Images or All Media to ‘Uploaded to this post’ the pictures are there and useable. When I leave that post and go to make another post, the pictures appear in All Images section where they should. *shrug*
It’s not a huge problem because I can still find the pictures and use them. Just not how it’s supposed to work.