frhdl

OK, found the solution last night myself:

You simply have to enter a value, not only a key, and everything is fine. I just tried to create the custom fields empty and then fill them with the appropriate values afterwards, which WP apparently does not allow. So not a bug, at least not technically, but surely in terms of user guidance/usability.

I forgot to add that i’m not using any plug-ins dealing with custom fields (in fact i’m not using any plug-ins at all for the time being), so that can’t be the source of the above problem…