Guests can only insert images one by one, and must save the post every time to do another insert

Hi, although we've allowed both guests and login-people the same rights to upload images, guests can only insert images one at a time. And every time they'll have to save the post to add another image. While with people who've logged into, they can insert images directly into the post multiple times.

Please see attached images.

Feel free to test the behaviours at our site: hkermall.com

(We'd like even guests to be able to insert images multiple times.)

Thanks

Ed