Is there some sort of trick to doing this? I've tried on two separate occasions by clicking the mithril icon at the top of the Instance Finder. Both times I immediately started a 105 FI after 'payment' (confirmed mithril coin balance reduced), and the FI daily quest did not appear once inside.
Do you have to do it for both 105 and 100-104 before it works or something along those lines? Any ideas why it might not have worked (twice)?