Other users reported in another thread that this happens when you change the setting to "friends only". This problem should be fixed now. Can you please confirm?
Does the problem persist? Did you try refreshing the page in your web browser?
To test this I logged in as you (I can do this because I have admin privileges) and I did not have that problem. I tested it with a Google Chrome browser.
Since this training is public, nobody should get this message, no matter if logged in or not.
I can't open one of my trainings
http://www.gps-sport.net/trainings/running_187093
I get the message that it is not public, althought it's my training.