Presuming Wu Kong wasn’t active, and the tiles matched weren’t the same color as the Titan (since those won’t stun a Rare Titan), then yes, that sounds like an odd issue happening.
If you can, I’d suggest videoing your Titan hits to see if you capture it happening again.
In the meantime, you could try contacting Support to see if they can perhaps investigate their logs to understand better what was happening — though I’m not sure they’ll go into that much without screenshots or video to demonstrate the issue.
If you do want to contact Support, the instructions are here: How to Contact Support (Version 31 Onwards)