I've learned from your support that the transactions that has taken place in Zoho Books will be only reflected in the sales report. The same goes to the Payments received reports which will reflect only the payments that has been recorded in the system. 

If you import these data, running these reports will return nothing. 

This is indeed a show stopper, otherwise why the import function?

I hope this can be fixed as all the data is already there.

Thanks.