AsciiDoc highlighting doesn't colour the 2nd text-block connector correctly

[Alberth289346]

Version/OS info:

$ cat /etc/os-release 
NAME="Linux Mint"
VERSION="21.1 (Vera)"
ID=linuxmint
ID_LIKE="ubuntu debian"
PRETTY_NAME="Linux Mint 21.1"
VERSION_ID="21.1"
HOME_URL="https://www.linuxmint.com/"
SUPPORT_URL="https://forums.linuxmint.com/"
BUG_REPORT_URL="http://linuxmint-troubleshooting-guide.readthedocs.io/en/latest/"
PRIVACY_POLICY_URL="https://www.linuxmint.com/"
VERSION_CODENAME=vera
UBUNTU_CODENAME=jammy

$ apt list xed
Listing... Done
xed/vera,now 3.2.8+vera amd64 [installed]

Issue Asciidoc allows to have multiple text-blocks in a single item of a definitoin list. You do this by typing a + at the line between the text-blocks.

Xed hides the + connector before the 3rd text-block (didn't try more text-blocks). It doesn't color it in the same way as the first connector (between the 1st and 2nd text block).

Steps to reproduce

1. Open a new xed, switch to asciidoc highlighting (eg xed a.adoc at the command line).
2. Type the following

== An ASCIIdoc

Something::
Text of the something
+
Second text
+
Third text

MoreSomething::
Text of the something
+
Second text

Third text

3. Observe that the + below Second text is coloured differently (and in fact invisible to me):

Same text, but selected:

Rendered as html after asciidoctor something.adoc. Note how the + has semantic meaning, in the MoreSomething item the Third text is not part of the definition any more, it's text below the definition list.

Expected behaviour

All lines with a + should be rendered in the same way

[Alberth289346]

As a side-note, writing a new text, and saving that as something.adoc doesn't trigger enabling the asciidoc highlighting mode.