I find if I use Windows Explorer they don't seem to upload but if I use Google Chrome or Firefox they upload quickly and easily. Hope that helps.
There post in the Q&A that might help with this. I have added a link to one. Let us know if this helps.
There could be many reasons for this, such as, if Miss Veronika was doing update work on the site. Most people with trouble uploading find that the picture has too many pixels and that reducing the size or detail in the photo takes care of this. (I don't know how to tell you to do this!)
The pictures must be under 3 Mb, which is still very detailed. I have used Paint to reduce the size to comply with the standard size Designs by Sick asked for.