Downloading an "All-in-One" (AIO) codec pack is the most reliable solution as it supports multiple architectures. MX Player EAC3 Audio Not Supported FIXED!
You downloaded the wrong architecture (e.g., ARM64 codec on an x86 tablet). Uninstall MX Player completely. Reinstall from Play Store. Do not reinstall the custom codec. Use VLC instead. eac3 audio format not supported in mx player