Chrome Version: 67.0.3376.1 (Official Build) canary (64-bit)
OS: macOS 10.13.3

What steps will reproduce the problem?
(1) Go to Google internal Hangouts Chat (chat.google.com)
(2) Load a room with long threads that need to be expanded.
(3) Expand a thread with many messages.

What is the expected result?
You should see user names and profile photos on the left beside the chat messages.

What happens instead?
Most user names and profile photos are invisible. The chat messages sometimes flash as you scroll around. You can click on the invisible user names and profile photos.

This is on a Macbook Pro 15 Mid 2014 with Nvidia Geforce GT 750 and Intel Iris Pro