I'm not familiar with Simple Start, but I gather you used a trial version of Quickbooks 2014 for Windows to convert the SS2008 file and subsequently to save it in QB Mac format to open with QB Mac 2014? If not, repeat the conversion process to be sure you get as much of your data moved over properly as possible.
The Unbilled Time and Costs in the new Income Tracker is one of my favorite new features of QB 2014 for Mac. But, yeah, if it is showing things that don't belong there due to the conversion, let's clean them up!
There are a couple of ways to go about the cleanup. The easiest is the way you began with: the Unbilled Costs by Job report. Really weird that the report is blank even though the Income Tracker lists a number of your customers. (And, you're sure that they ARE unbilled... you clicked the blue Unbilled Time & Costs button and each customer line begins with "Unbilled Time & Costs", right?)
With the Unbilled Costs by Job report open, it should be displaying all dates, but the conversion from SS2008 must have marked some things as "billable" that should not be. Click the "Filters" button near the top left of the report window. Uncheck the lines for Account and Posting Status. Click the Apply button.
If your unbilled transactions now show up - just go through each one, double-clicking on the amount field to open the corresponding transaction where you can uncheck the 'billable' field.
If you still don't see the unbilled transactions, then there must be some kind of corruption in the data import. Do a File > Utilities > Verify Data to make sure that's not the case.
Then... the slowest way to clean this up would be as follows if the above didn't work:
You cannot double-click an amount in the Transaction Center for these unbilled lines to get to the transaction. Instead, use this tedious workaround:
1. Hover your mouse over one of the lines in the "Type" column that reads "Unbilled Time & Costs". You'll see a tiny round button appear with a ">" symbol. Click it... and then click the "Create Invoice..." pop-up menu.
2. You'll see a new Invoice window appear (ignore it - we won't record anything) - and on top of that will be the Choose Billable Time and Costs window. All tabs will read $0.00 but you need to look at each tab to find the billable expenses - most likely under the "Expenses" and "Items" tabs.
3. Let's say you found an entry under the Expenses tab. Unfortunately, you cannot drill down (double-click) to the actual transaction. You simply now know the date of the transaction and the vendor.
4. Close the Choose Billable Time and Costs dialog for now (its modal - cannot do anything while it's open)... and switch to the Vendor Center, click the corresponding vendor and find the transaction date in the list of transactions (setting the filters to All Transactions / Show all / All Dates if not that way already). Double-click the transaction to open up the Bill/etc window that shows an amount as Billable and clear the Billable checkbox.
I don't know of any faster way of doing this (other than with the Unbilled Costs report). Not something I've ever had a client have to do. A shame that your data came through this way.