Can't upload images to soundcloud

When trying to add artwork to a playlist on my Soundcloud profile, I click the 'add artwork' button and then I begin to browse my computer for an image to add. I have a specific image which I always use for my weekly playlists, it's a jpg, and the resolution and file size specifics are within the acceptable range listed by Soundcloud, however my file is greyed out and I can't select it. As I say, that is an image I have used many times in the past and it used to load fine. I've even tried changing the file type to a png which is also acceptable, and also tried changing the resolution, but still no joy, I can't select the image to upload.

I've tested uploading the same image in Chrome and it works fine, so it appears to be an issue isolated to Safari.

I have recently updated Flash, but that's the only change I can recall making recently.

Is anyone else experiencing image uploading issues with Safari. Are there some settings in preferences that I can check to make sure the image should upload correctly?

Thank you.