To check the configuration when importing your customer's, I recommend reaching out their Technical Support Team since TSheets is a third party app. They can review the connection setup between TSheets and QuickBooks Online (QBO) and help you get back on track.
To reach them, click the (?) icon from your TSheets account and select Product Help, then Chat Now. You can also check this link for more information to connect with them: Contact TSheets support.
For more information about how QBO integrates with TSheets, see below links: