Over the weekend, some developers faced an issue where Team Create failed to sync with our servers, and this bug would reset your work intermittently. This was caused by specific situations related to the newly added dialog when you exited Team Create. The dialog would simply prompt a user to confirm if they intended to close the Team Create session.
Unfortunately, one of the edge cases that emerged was how the dialog would impact developers who disconnected from their Team Create sessions and reconnected. Choosing to not close your Team Create session after a disconnect would open two Team Create sessions of the same game. Having two sessions open of the same Team Create game would cause synchronization issues with our servers, and could lead to you losing your work.
This feature was turned on starting Thursday, August 27th. We linked the synchronization to this dialog on Saturday, August 29th, and have disabled the feature.
We are working on a fix and hoping to re-release the dialog in the future. This was strongly requested by the developer community, and it is something that we would like to include as it is a Quality of Life (QoL) change.