"New message" indicator is not seen when posting a message in RHS

Description

While testing https://docs.google.com/spreadsheets/d/1xdTyBHh-1GHugpLwzmdScbXWNSnuTOu8yNg_rNfo31E/edit#gid=1194273465

Repro
1. User A: Scroll up in the center panel in Town Square
2. User A: Click the reply arrow for one of the messages to open the right-hand sidebar
3. User A: Post a message in right hand sidebar

Video attached.

QA Test Steps

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Status

Mana

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Assignee

Unassigned

QA Assignee

None

Reporter

Ali Farooq

Epic Link

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Fix versions

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Mattermost Team

Unassigned

Sprint

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QA Testing Areas

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GitHub Issue

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Components

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