If you are an existing user users in Celoxis and decided to switch to QBO have been invoicing time entries in Celoxis, you need to first agree on a date prior to making the switch. This is important essential because once you are connected to QBO you can only sync the post connection you cannot invoice time entries which in Approved and Billable state. You cannot invoice entries from Celoxis. Invoicing will has to be done from QBO. Entries in Approved will not have Invoice option however you can delete, reject and modify the fields of time entries. 
QuickBooks Online.
All existing Invoiced time entries will not be synced with QuickBooks Online. These entries will continue to retain the v9.1 behavior till the time they are explicitly “UnInvoiced” by a privileged user
The time entries will not have invoice and UnInvoice option.
*******IMAGE
Time entries Invoiced in Celoxis prior to connecting to QBO will not sync with QBO, If you wish to sync these entries with QBO you need first UnInvoice them so they go back to Approved state and you can sync them with QBO. (Note: Only user with admin rights can UnInvoice Time Entries in Celoxis)Only approved and billable time entries can be synced.
