Syntax highlighting goesn't highlight second keyword on planning line

[tbm]

With a file like:

* TODO Test
SCHEDULED: <2020-07-09 Thu 16:00> DEADLINE: <2020-07-09 Thu 21:00>

SCHEDULED is highlighted but DEADLINE is not. If I put DEADLINE on a separate line, it gets highlighted.

But my reading of the Org spec is that they have to be on the same line:

https://orgmode.org/worg/dev/org-syntax.html#Clock,_Diary_Sexp_and_Planning

where HEADLINE is a headline element and PLANNING is a line filled with INFO parts, where each of them follows the pattern:

KEYWORD: TIMESTAMP

Note the: "a line filled with INFO parts".

[tbm]

@FlorianMickler does your PR #314 fix this by any chance?