Crash/freeze when applying Optical Flow time interpolation to clips - PP CC 2018

[Joe @ F8]

DESCRIPTION OF PROBLEM

The problem consistently happens when I attempt to render a clip in my sequence after the spend/duration has been changed (slowed down) with the "Optical Flow" Time Interpolation selected. Immediately after entering the Render Selection command on this single clip, the entire computer locks up completely. (This isn't an application freeze, but rather a complete system lock-up (no input from mouse or keyboard) and requires a force-power-off of the computer using the hard power button.

After re-launching PP and attempting the same action on the same clip, I get the same results. Ruling out a corrupt clip/file, I removed the problematic portion of my sequence and edited for about an hour without any problems, but when I attempted to create the same effect again on a different clip/file, I got the same results immediately when I tried to render. (To further complicate things, I have been able to render with Optical Flow in other projects, but it doesn't do anything—it just renders as if I've chosen Frame Sampling.)

COMPUTER INFO

• iMac (Retina 5K, 27-inch, Late 2015)
• macOS High Sierra (10.13.1)
• Processor: 4 GHz Intel Core i7
• Installed memory: 32 GB 1867 MHz DDR3
• Graphics: AMD Radeon R9 M395X 4 GB

HARD DRIVE INFO

• Working from a Gigabit network-connected Synology DS1817+
• WD RED 4TB drives (x8) – I believe they are SHR (Synology Hybrid RAID)

PROJECT INFO

• Premiere Version: Premiere Pro CC (2018 Release) 12.0.0 (Build 224)
• Footage: Canon C100 Mark II, MPEG (.MP4) 1920x1080, 23.976fps
  • Recorded at 59.94fps and slowed to 23.976 in-camera using the "Special Recording - Slow & Fast Motion" function
• Renderer: Mercury Playback Engine GPU Acceleration (Metal)
• Red Giant Universe is the only plugin installed; some effects being used (sparingly) in this project, but not on the clips in question
• TRT of timeline: about 5 min

[LucidFilms]

has you resolved this issue?   I am having the exact problem.

[Joe @ F8]

Unfortunately, even after updating I could not get my 2 existing projects to render these effects correctly. A new project I started after updating has been rendering as expected (for now), so perhaps the update fixed my issue for new projects… But it bothers me a lot that I'm still unable to render those original two projects as desired—and they suffer a loss in overall quality as a result.

[excited_Genie16B8]

Now that's a well stated original question. 

[hyperottawa]

I have EXACTLY the same iMac configuration, and even the same Universe plugins. As soon as I changed the renderer from Metal to OpenCL the clips render without system freezes.

[Jonzy]

I had a critical freeze on my MBP, also by using optical flow procedure. Like the suggestion above I switched from Metal to OpenCL. It fixed the problem for me.

[francis-crossman]

We are looking into this.  I can reproduce this on several Mac systems.  The current workaround is to use OpenCL renderer rather than Metal.  Please feel free to file a bug here - User Voice