It's working for me.... I did have a problem a couple of weeks ago..... where it took FOREVER to load.
Here's the route I take to copy/paste an image into a thread here on the forums....
Pick the photo you want and left click on it....
When the individual photo comes up..... left click on it, and the background should change color.....
Scroll down and on the lower left, click on "embed codes"
Under the headding "Full Image"........ go to "BB Code" and place your mouse pointer at the right end of the URL in the box......
A button that says "copy" will pop up....
left click on the "coyp" button, and then go back to the tab in your browser where Knifedogs/the thread you want to paste into is up/open...
Left click where ever you want the image to be, then right click for the context menu......and then left click "paste" .......
ALL DONE!! The URL from ImgBB should appear, and will chage to the image upon posting.
If you already knew that....sorry.