why Prepaid expenses didn't posted expense transactions?

The reason you're not seeing those expense transactions posted yet is due to the scheduling process.

In QuickBooks Online (QBO), a status of Pending means that the system has successfully set up the schedule but is waiting for the scheduled dates to arrive. Once each date on the schedule occurs, QBO will automatically post the journal entry and move that portion into your expenses.

If you want to post the entry immediately, you can manually click to Post or Approve it directly from the Prepaid expenses schedule screen to process it early.

Please feel free to reach back out if the entry doesn't post smoothly or if you have any other questions as you navigate the schedule. We're always happy to help.