Successfully converted: 4K HDR to 4K 60FPS 8 Bit SDR but now it plays in slow motion

[Selur]

MAYBE you mean this:

no, the start of that log:

This log is only intended for user information. It should not be part of a bug/problem report!!

should indicate that. (read the sticky)
That that the warning shown there:

Not using InterFrame since input (25) is less or equal target (25) fps!

Indicates that you didn't configure InterFrame to interpolate to 60fps. (or that change wasn't propagated, which like I wrote should reflect in the x264 call)

Cu Selur