Use the Horn of the Vastiri to clear the Sandstorm

Im stuck in act 2 cruel with use the horn of vastiri to clear the sandstorm. I couldn't progress with this quest, probably because i killed boss in halani gates while having horn in my inventory. I tried to fix it by dropping horn to the ground and it disappeared. Can't progress this quest, played 28h already...
Please fix this

I uploaded this to reddit too, hopefully you can solve this soon https://www.reddit.com/r/PathOfExile2/comments/1h9kc85/the_trial_of_corruption_softlock/

same gg. cannot continue in story

I'd imagine someone figured out that you have to do something AT the caravan. this is totally unintuitive, more than a year old, and needs the smallest adjustment.

Like, place a quest marker at the place where we need to play the horn. Or let us use the horn AT the storm.

One or the other or both. This is very stupid and very old and very fixable.