Hi Yves,
Ok, so I have done a little more testing of this. I don't think I'm going mad, but anything is possible!! This is what I did and the results.
1. I regressed the CSS to remove the fees from my site.
2. Clicked into an event detail page whilst not logged on to the site. I could see the ticket price (see screenshot).
3. I logged onto the site with a test account and went to the same event detail page. I couldn't see the ticket price (see screenshot).
4. Whilst logged in using the test account I signed up to the event. I could then see the ticket price when I went back to the event detail page.
All a bit odd. Like I say, not really a problem for me as my events will be free when I eventually get my site live. And I'll put in the CSS you advised to remove the price. But always nice to get to the bottom of things and it may help others.
I have tracked back in my change log and nothing in there that would cause this. Only changes made have been to the language files and an override to place the map at the top of the page on the eventlist page. Nothing obvious that would cause this.
Let me know if you want me to check anything else.
thanks Pete