I was going to ask the same thing. The indicators speed up when the detect a failed bulb, ie zero current flowing. LEDs draw so little power that the system sees it as failed, and speeds up the flashing to alert the driver to the fault.
This is a classic and deliberate behaviour where there is a blown bulb or someone has fitted the wrong type of LED replacement. Because the OP claimed that all the bulbs were working I dismissed the idea - AFAIK when the fast ticking occurs there are also fast indicator flashes but not sure if this is necessarily the case..
If you fit LED bulbs then they will "work" but return the wrong resistance so the BCM or whatever it is that controls the electrics thinks a bulb is blown and does the rapid click thing to alert the driver.
It would be really helpful about now if the OP actually answered this question???