I use Safari. I was able to copy an image into the post field when the “insert image” upload failed repeatedly.
Here’s how:
In WordPress’ menu, select the main category “Manage,” and then the subcategory “Media Library.” You will see all of the images (probably many duplicates) from your failed upload attempts. Now simply right-click on the image you want and select “copy image.” Then return to the post you want to insert the image into and right-click and paste the image into the post field where you were trying to upload it to. This worked for me in Safari. I’ll bet it would work in other browsers too. I was unable to do the same with an audio file but at least I’m able to get my pix into the posts until a fix is provided for us. Hope this helps.