This is as expected. The WBI web application does not have all of the same abilities as the desktop application due to the nature of it being a web application.
The WBI web application does not send data entered back to the database until you initiate it to do so - i.e. enter in details in a Labor record, but it is not saved to the workorder until you tell the application to accept that labor record by selecting the checkmark and selecting the Save menu option for the workorder as a whole.
What this means is, is that WBI does not “know” what to be able to initially fill into the Service Quantity Rate field because it does not read what has been entered in the Start and Stop fields until after you have completed saving the entire record.
As the record has been completely saved , AyaNova will not modify the saved record changing the Service Rate Quantity, as whatever you manually had entered in there could certainly be different than that derived from the difference, and AyaNova will not modify the record after it has been saved.
With WBI, the Service Rate Quantity field is not automatically derived - this is so that you can manually enter in whatever amount you wish and not have it overwritten.
When entering in labor using WBI, enter yourself in your billable amounts in your Service Rate Quantity field.