Assignment of receivables would mean sale of the lease rentals, not the asset. In that case, the leased asset still remains the property of the assignor – that is, the assignor has retained the residual interest in the asset. However, it would be different if the lessor sells the asset that has been leased out.
Average accounts receivable is calculated as the sum of starting and ending receivables over a set period of time (generally monthly, quarterly or annually), divided by two.