AME hangs when outputting webm VP8 only (OK with VP9)

Good afternoon,

Thank you for taking the time to ponder a quick issue..

I am very new to  AE/AME, but I've put together a 5-second sequence that I can export to various formats successfully, including mp4 and webm.

However, I see a noticeable drop in quality when I upload the webm file to Gfycat. Apparently for best results that needs to be uploaded with VP8 (among other things), but after some troubleshooting I finally narrowed down the problem in AME to that setting: The render freezes 12-15 seconds into the process, and the CPU maxes out indefinitely and the program hangs. No problem if I use VP9.

1) What settings could be related to this problem? I've already restarted both programs. All current versions of CC.

2) Is there a more direct way to get a high quality GIF without having to upload a webm to Gyfcat? When I try to create one directly I get color banding even with the highest settings. My web builder doesn't allow me to embed webm.

I can add more information as needed.

Thank you