When you contact IFTTT, I would recommend pointing them to this forum post which discusses an Asana update now occurring:
Asana is moving from numeric to string IDs and that’s my bet as to why it stopped working. If I’m right, then note that it will start working again later today, as (per that post) Asana just changed it for 24 hours in order to surface issues like this one. IFTTT then has another 2 weeks to update their service before it breaks again for good on October 29th.