I'm not familiar enough with Blu-ray players to know, but the fact that it played when changed to a different format may indicate Blu-rays recognize only certain formats.
On a Mac since 1984. Currently: 24" M1 iMac, M2 Pro Mac mini with 27" BenQ monitor, M2 Macbook Air, MacOS 14.x; iPhones, iPods (yes, still) and iPads.
