I hear you and have been on tech support with the same question with no solution from within QB Online.  I created my own MANUAL WORKAROUND VIA EXCEL for Monthly Report.

1.  Turn on Locations and identify your transaction within the proper accounts such as Petty Cash, Checking, etc.

2.  Generate and print your Profit & Loss report with Locations:  Include Petty Cash and Bank transactions.  

This report will print each in a separate column.

3.  EXPORT report to Excel.

4.  Open Excel.

5.  In Petty Cash column under REVENUE, Manually add 2 LINE ITEMS:

Opening PC Balance (Fill in amount manually) 

PETTY CASH:  (Fill in amount manually transferred to PC).

6.  Adjust your formulas to include these additions. 

Balances will coincide exactly with Bank Statement and PC reconciliations.

7.  In Bank / Checking column, under EXPENSES, Manually add TRANSFER to Petty Cash

8.  (Manually) add the amount transferred in the month.

Not perfect, but it gives me what I want to see all in one place.