Chat multiline markdown is wonky, but the rules are pretty simple: Only code and quote work. And only if they're applied to the whole message.

@Chippies Multiline does not support markdown.

@RedRiderX Multiline Markdown does not work.

Multiline markdown is not a thing that works in chat.

@MichaelDunfield Quote and Code work multiline.

@RavenDreamer You wouldn't believe how often I say that.

@RavenDreamer Multiline Markdown is not supported.

With the exception of four spaces for code, no markdown works in a multiline message.

Four spaces
is the only
multiline m
arkdown tha
t works

@TrentHawkins Multiline markdown no work.

@Fluttershy Multiline Markdown is bad.

Also, why doesn't multiline formatting work?

@fredley A new button shows up on multiline.

@jeffreylin_ Multiline formatting does not work.

Multiline formatting b bad.

@jeffreylin_ Multiline formatting doesn't work.