How to copy/paste parts of a text in Messages.app

I am pretty sure I used to be able to select and copy text in Messages.app like in any other app (click + drag, double-click, etc.)

Right now I don't seem to be able to do this.

I am not sure what updated last, I am on macOS 10.14.6, Messages.app 12.0

Use case:

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How do I copy the code from the message?

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Looks like it was a bug.

I restarted Messages.app and now it works as expected (and as it should have done in the first place)

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I'll keep an eye out and edit this answer if I figure out what causes the bug.

It does have an odd behaviour, but one that's easy to work round.

If you click-hold, the 'reaction' pop-up will appear, so the trick is just a short click.

If you click once straight onto the message bubble, anywhere, the text goes grey. At this point any interaction is with the entire message. If you directly double click or right click whilst the text is initially black, it doesn't go to grey, you can interact directly.

Basically, don't do that first click. You can do anything else & it works as individual words - so right click, double-click or click-drag works, for instance.

If you click outside the message bubble, the text goes back to black & you can now interact like any ordinary text.

BTW, verification codes like that will be found by Safari & will click right into the web page.

Examples