AE Beta 17.1.4 Build 2 / FPS error

[Ko.Maruyama]

Steps to reproduce:
    1. Import movie .mp4 for rotoscoping
 Result:

movie is recognized as .AVI and is interpolated in rotobrush - produces green frames. (does not seem to be due to RotoBrush 2). 

Expected: ...

Green frames do not appear in previous versions of Ae 

previous versions of Ae have different frame rate interpreted.

import produces green frames (strange frame rate on import)frame rate is strange (from client) but is interpreted as different FPS in beta which produces green frames. Changing interpolation does not solve 'green frames'

System info
    Application: After Effects (Beta) v17.1.4.2
    OS: macOS v10.13.6, RAM: 128.00 GB, CPUs (logical): 36