In an attempt to get TrueHD working in passthrough I decided to update both BIOS and HDMI firmware on my NUC.
So now I actually got TrueHD passthrough, yay!
But instead I am now missing refresh rates above 30 Hz for 4K resolution 3840x2160, which I am pretty sure was working before the upgrade.
I found this thread from Thomas_AR discussing HDMI firmware on the NUC8 too but they were not mentioning refresh rates I think: Intel NUC 8i5BEH - HDMI Sound problem
Current setup
LibreELEC-Generic.x86_64-9.95.4
Intel NUC8i7BEH -> Marantz SR8015 -> Sony XF90
BIOS: BECFL357.86A.0088.2021.0330.1431
HDMI firmware: 1.78.4.0.4 (MCDP2800_C21_C22_V1.78.4.0.4_LSPCON_MP_FHC_SIGNED_CMDB_BE_210309)