You've got me here and I'll share a workaround to help you offset the transactions, sc38.
Before doing so, please make sure to consult your accounting professional for advice. To begin, let's create a wash or clearing account. This is a temporary account to move money when the transfer cannot be done directly from one account to another.
Here's how:
- Go to Accounting > Chart of Accounts.
- Select New and choose Cash and cash equivalents from the Account Type drop-down menu then Cash on hand from the Detail Type.
- Add the name of the account as ‘Wash or Clearing Account’ (this account will be zero out after the process).
- Click Save and Close.
Next, create a journal entry to transfer A/R to the Wash account:
- On the left panel, click + New > Journal entry.
- Set the Journal date.
- Select the Wash or Clearing Account on the first line and add the amount in the Debit column.
- On the second line, choose the A/R or Trade and other receivables account and put the amount in the Credit field. Make sure to add the customer name from the Name column.
- Click Save and close.

Next, record a journal entry to transfer the amount from Wash account to A/P or Trade and other payables account:
- On the left panel, click + New > Journal entry.
- Set the Journal date.
- In the first line, select the A/P or Trade and other payables account and add the amount in the Debit column. Make sure to select the supplier name from the Name field.
- Select the Wash or Clearing Account and put the amount in the Credit field.
- Click Save and close.
Once done, follow these steps to the apply the journal entry:
- On the left panel, click Expenses > Supplier.
- Select the supplier's name and find the bill.
- Click the Make payment link and put a check mark on the journal entry box under Credits.
- Hit Save and close.

Finally, close out the receivable transaction:
- Go to Sales > Customers.
- Click the customer's name and select the Receive payment link of the invoice you want to close.
- In the Receive Payment window under Credits, put a check mark on the journal entry box. Make sure there is no amount on the
- Amount received field if you are just applying the credit.
- Hit Save and close.

To learn more about journal entry, you can read this article: Create a journal entry in QuickBooks Online.
Please reach out to me if you need further assistance. I'm just a post away to help you out some more. Have a great day!