It still does't work. Atm I've got following set under
user setting,
global system settings is untouched:
filemanager_path - /assets/upload/
filemanager_url - /assets/upload/
rb_base_dir - /assets/upload/
rb_base_url - /assets/upload/
strip_image_paths - No
I've also tried to set "strip_image_paths" to NO in global system settings.
Some progress:
Changing "filemanager_url" in global system settings to "/assets/upload/" does the trick for the customer/user. Unfortunately it doesn't play well with the Admin account. When I'm updating any resources with an image set, the first part of the URL containing "/assets/upload/" from system settings is generated twice e.g. /assets/upload/assets/upload/flower.png
What a mess..zZz.. Gonna sleep on it.
Thanks for your help and suggestions.