You cannot define margin or padding and a direction at the same time.
<Grid marginBottom="S" margin="L" />
is invalid because it's ambiguous: is
"L" a valid for margin bottom?
If you want to define a different bottom margin value you can do so by either specifying all margins as individual props:
<Grid marginTop="L" marginRight="L" marginBottom="S" marginLeft="L" />
Or using the shorthand syntax, as follows:
<Grid margin="L L S" />
You can find more information on how the valid spacing formats here.
Updated less than a minute ago