TikTok Shop says it's connected to a Shopify store, but Shopify says it isn't. I'm completely stuck

I'm running into a weird issue and I'm curious if anyone has seen this before.

I'm trying to connect an e-commerce platform to an existing seller account, but I keep getting an error saying the account is already connected to another platform.

The problem is that the original platform/store was closed a long time ago. I've checked every settings page I can find, including app authorizations, integrations, connected assets, and account settings. There is nothing listed that I can disconnect.

I also contacted both companies involved. One side says there is no active connection on their end, while the other side continues to report that a connection exists.

At this point it feels like there may be some kind of stale backend record that isn't visible in the user interface.

Has anyone experienced something similar where an old integration continued to block a new connection even though the original store/account was gone? If so, how did you get it resolved?

Any ideas would be appreciated.