I've recently started getting this error on my encodes for Blu-ray:

[libx264 @ 0x7fcc7160c040] timebase mismatch with 1st pass (1/24 vs 1001/24000)
Error initializing output stream 0:0 -- Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height
Conversion failed!
The settings for both passes are identical, any suggestions?