It’s really annoying that you can’t turn the air raid siren in the light house off. If you activate it in a MP game it will sound forever and over most of the island. It’s gets really annoying after a while.
The little indicator light on the pole with the button changes but the siren still makes it sound.
I can confirm that this issues is also on Xbox in single play as well as co-op. @AUS-ARMY_22 & I ran into this as did myself & another player. @Zesiir this might make your list I checked & did not see it there. @Alinde here is a “popular bug” list for you to check & like I said I did not see this bug there but, the list may be of help in the future.
SPP
Yup, had this happen last night during M.P. . It got real annoying real quick. We ended up quitting the game prematurely because of not being able to shut it off, and the volume being so high no matter where you went. We couldn’t even hear the NPC’s over the horn.
Hey guys 
This issue has been reproduced in-house and we are working on a fix for it.
Workaround:
In the meantime, to get rid of the air raid siren you can restart the game (it’s not enough starting a new session as the air raid siren will persist, a full restart is required).
Sorry for the inconvenience and thanks for reporting! 
Happened to me as well (xbox1) but I was actually hoping I could attract a swarm of bots to upgrade rivals,etc but sadly they all seemed annoyed by the siren as well so they stayed away from me , sigh…