Version: 56.0.2913.5, 56.0.2919.0
OS: 7.1.1 NMF27F

What steps will reproduce the problem?
(1) Open Inbox app
(2) Open message thread with many messages
(3) Note that content of last message is displayed
(4) Expand the message thread by scrolling up and tapping the first message
(5) Now scroll down to the most recent message

What is the expected result?
Most recent message displayed

What happens instead?
Message not displayed, blue spinner shown indefinitely

Please use labels and text to provide additional information.
Does not repro on latest M55 beta, 100% reproducible on M56 dev / canary.