I too believe they are (multiple) LEDs - which was why I was going down the route of checking electrics
However.
Whilst the manual doesn't specify which fuse covers the indicators (under bonnet fuse 22 is hazards), the fact that the front and rears work seems to rule out a blown fuse.
Working electrical mirrors also
seems to rule out a loose connector block (though I guess it might just be hanging on in).
Which would - again seem - to indicate (sorry!) the bulb(s)
TTDegs wanders off to think some more...