With a quick test, created and type were a text type; up and related were a list type using the above template. Try removing the brackets for those. e.g.
<%*
let title = tp.file.title
if (title.startsWith("Untitled")) {
title = await tp.system.prompt("Title");
await tp.file.rename(title);
}
tR += "---"
%>
created: <%tp.file.creation_date()%>
type:
up:
related:
alias:
tags:
---
# <%* tR += title %>
---
<% tp.file.cursor(0) %>
Running this gives me a list type for the first four Properties.