[Ghitulescu]

IIRC that Onkyo is made by Funai (as OEM) on Panasonic basis. A very restricted player like all based on the Uniphier chip.
If made after fusion, could be based on MTK instead (like Oppos that played almost everything).
I might expect the AVR play more formats than the BD player.
The best solution is to have BD-RE (25 or 50) and burn them.