Welcome to the forum. Sometimes the glass fuses can be good but the contacts may be corroded. It's sometimes not obvious that the fuse wire is broken if the break is behind the metal contact at the ends of the fuse. I suggest a continuity test of the fuse or swap fuse and clean fuse board contacts.
I have no idea of it is the same but I had similar symptoms on my Corniche about 2 years ago not long after I bought it.
Fuses and relays for the headlights all OK - ( I was amazed how many relays the things has - and dotted all over not just in the main fuse box!.)
But there is also another relay for switching main to dip beam - its much larger than the usual relays, with 5 cables if I rember correctly - mine is under the bonnet, fairly close to the suspension on the left hand side.
It was expensive too - something like 130 euros, but solved the issue.