1. 24p auto
It seems that using some AV receiver and in particular HDMI 1.4 ones, the 24Hz auto mode is problematic. In this case, on the home page, click the SETTINGS button, then the video settings, and then, at the bottom of the page, uncheck the option "Auto 1080p 24Hz Playback".
2. HDMI cable
Some even high-end HDMI cables do not pass enough bitrate to properly passthroug sound and image. In this case, please make sure that all your HDMI cables used between the player and the AV receiver and used from the amp to your TV are HDMI 2.0 certified (18 Gbps minimum). If they are not, please replace it.