Ifttt webhooks

I’m trying to troubleshoot why the webhook component for IFTTT doesn’t work for me. When I try sending an event from HA it fails silently. From curl it says wrong key. Even the webpage on the IFTTT webpage where you can try the webhook fails with a test event (that works if I trigger it some other way). The key is pre-entered in that case, so I can’t see how that could be the problem. I have renewed the key many times to no avail. Any ideas?