Excellent observation! I just confirmed what you said and found that loading images while in bb code mode only works when you use the attach files button:One thing I have found that MAY be causing an issue for some people is that the toggle BB code button does strange things to image uploading.
I typically upload by grabbing a picture and dragging it into the text box but that doesn't work if the BB code is toggled the wrong way, it just pops up another tab with the image. I have figured it out and it is no longer causing me issues but it could be something causing some of the glitches.
When in bb code mode, one cannot load pictures using the mountain or gallery icons: