why IR/ISO cannot generate Intercompany AP AR ?

Under the same SOB but different OU ,IR/ISO process cannot generate Intercompany AP AR,why? which IR/ISO process can generate IAP/IAR?where to define Supply site?

Thats not correct. You can

Thats not correct. You can always generate Intercompany AR/AP invoices if the transaction involves two different operating unit. It doesn’t matter if it’s in same SOB or in different SOB. Yes. you can’t generate intercompany invoices within same OU (between two inventory organization) and that’s quite logical.