Same here. Have you had any success with this since your comment?
I noticed that there is no All Integrations to click on any more (at least, not that I could see), but there was a Legacy Integrations instead. So maybe this Trello thing doesn’t work any more?
ps there’s a video in this blog that shows where the Create Trello Card button issued to appear: https://blog.sentry.io/2017/12/22/twelve-days-trello