Emojis not rendering consistently in markdown

[LarkRanger]

I want to insert a few emojis into my rmarkdown document.
However, when I knit my document in the emojis won't render.
In this example the chunk render doesn't work but the inline one does:

    Example for not rendering:

    ``` {r}
    library(emo)
    emo::ji('smile')
    ```
    
    Inline example:
    `r emo::j('smile')`

But then here the inline doesn't work as well:

<font color='skyblue'>*Hey, you! Marine biologist! I have need of your services!  
A sea turtle begins its life amidst great danger, and not very many of them make it to the water. See, I'm working on a big budget movie - think "Saw", but with turtles. Anyway, let's make some realistic numbers of turtles for me to... **keep alive.***</font> `r emo::ji('turtle')`

I've updated everything I could think of (R, Rstudio, all markdown-related packages) but alas, and so I come here to look for answers.

[patarol]

Same here. Using macOS Catalina (10.15.6) and R 4.0.2

[Kinzel]

Try to copy and paste the emotes. 😀

Use this page to copy them https://github.com/hadley/emo

[quantitative-technologies]

When I copy & paste into RStudio these are either black & white, or empty squares.

Does this mean there is a problem with my installation?