The accounts receivable report and summary are both showing in the company base currency (omr). However the customer is invoiced in EUR
The GL ledgers of the Debtors in Euro was created during setup , so those are showing up in Euro
I am using the latest development version of ERPNext.
ERPNext: v12.x.x-develop () (develop)
Frappe Framework: v12.x.x-develop () (develop)
Please refer this post