I have changed my password and uploaded the pictures again. I had a pretty scrambled password, nothing someone could guess, but I changed it anyway.
Thanks for your response.
I've checked the training from July 18th but could not find the photos - neither in our database nor in the file system.
Could somebody have access to your account? Please change your password. As far as I know, there has been no technical issue causing photos to be deleted. Also, nobody else reported this so far.
We did change the photo deletion procedure lately, but this cannot lead to unwanted deletions.
I made many pictures for example on http://www.gps-sport.net/trainings/Maastricht-Bemelen-Maastricht_1675599 and on http://www.gps-sport.net/trainings/Duurloopje-met-Brigitte%2C-Maastricht-Borgharen-Itteren-Beatrixhav_1671375. They were visible last week, but now they have disappeared.