I use Avalara (Taxes as Line items) module and my taxes are not syncing to QuickBooks
1. Take a look at the GL entries tab of the invoice in question. Do you see Sales Tax lines? If yes, navigate to step 3.
2. If not you might need to create a GL Account in ConnectWise PSA and QuickBooks Online called "Sales Tax Payable". The "Taxes as Line Items" module (Avalara) will treat Sales Tax lines as any other service item line.
4. Check that you have include Sales tax enabled in Accounting Package in ConnectWise PSA. Navigate to System |> Setup Tables > Accounting Package: