Hi Tycho, thanks for responding :)
the url shows a picture, but when i change the picture (by editing it, retouching it... it still shows the initial uploaded version.
so i edit: https://www.funwork.nl/Portals/0/images/tab1.png (edit it on the server with good 'ol paint)
saved it, made a copy to another portal on the same machine to show you the difference:
i can rescan/sync in assets of funwork, but it wont show the correct (new) version except when i use the full name+version:
as you can see the one with ?ver shows the latest and greatest, but makes using the normal (known) filename kind of unreliable.