So just to summarize (for anyone reading this later on, or if OP wants to include it in a bug report), you're ...
- at the Spirit Sentinel at location +1250, +300
- you're on top of it (practically humping the Sentinel's face)
- you're not invisible
- when you con the sentinel it says he's warmly/kindly/ally
- you are saying the phrase "'I will find how it all began" multiple times
- you are also trying the phrase "I am Heyokah" multiple times
- (maybe for good measure you're also trying the phrases "How can we rub it out?" and "What about the city's demise?" multiple times)
- there's no other wackiness going on:
- you're not in the middle of a duel (not sure this matters)
- you're not mid-link-death (this definitely would matter)
- you're not doing this mid-spell-cast (this would be hard to do on accident)
- you didn't delete your black fur boots (not sure they even matter, but /shrug they might)
... and he's still not responding. And what's stranger still, you've even attempted this on multiple occasions and had the same outcome.
Pretty weird.