It’s not finding any sales lines on Work Tasks matching the conditions. Are your work tasks in status “Reported”? 

Thank you for responding,  yes work tasks are in reported status 

And you have sales lines, that are not already on an invoice preview? If you untick “Task must be Reported”, what happens then? 
Which release is this for btw?

Its the first time of completing this task within the environment. 

Sales lines are there and are in the status “Invoiceable” 

Same error when “Task must be reported” is unticked