Add a picture [Sell a car] upload issue

Dear Flynax Support,

There's a a problem I cant fix on the "Add a picture" step. Pictures not uploading correctly.

Let me show you some print screens:

1. This is the normal "add a picture" view.
Attachment 627
2. When I add multiple images and click on the upload button, only 1 picture uploads successfully and can make it as Primary. The other images are not uploaded.
Attachment 628
3. When uploading one by one images, the first one is uploaded successfully and the others are just shown as blank pages after the first image.
Attachment 629

PS: When i go 1 step back, then 1 step forward or when i do a page reload , pictures are uploaded.