I host my pix at www.postimage.org and use a link to get them into the post.
I was running into this issue also and at first couldn’t figure out how to change the photo size then remembered that if you email a photo it should allow you to select the size. So you could email the photo to yourself, select a smaller file size then open the email and re-save it which should then upload. I selected large instead of “actual” size and still seemed to work. Sort of a hassle but it’s the only work around that worked for me.