Yes, that’s what I suspect in the meantime, even if the very friendly and helpful support of my host says that they double checked that no server caching is active. Well, I have to trust them since I can’t check it myself. I don’t understand the host’s settings (caching, PHP…etc.), I’m just a small “user”. 
Would you, Adam, be willing to have a look at my host and see if you can find something if I trustfully send you my login data via email? I know it’s not your business and your task, but maybe anyway…? I just want to somehow understand what the problem is and learn something from it. If you don’t want to or can’t do that, it’s not a problem, I can live with the delay, but it does affect the workflow a lot. Just tell me what you think about my suggestion.
Thanks for your help in any case. 
