A guess from the hip:

• import of *.CSP is followed by compiling it to *.CLS,  which is compiled to *.INT
• import of *.CLS doesn't necessarily trigger a compile
   

This reminds me of the ages-old service rule

1.  The customer is always right
2.  If it is not right, then #1. applies automatically

😁

I met a similar issue.
A new IDEA might be to fix the interface for IDEAS   😉

TestFor.inc
 

#define MyLoop(%count) set x="" for i=1:1:%count set x=$order(^%SYS("JOURNAL",x),-1) write x,! 

in Test class:
 

ClassMethod Mike()
{
	$$$MyLoop(7) Write ?5,$get(@$ZR," *** "),!
}	

Resulting in

PURGED
      ***
PREFIX
 
MAXSIZE
     1073741824
LIFESPAN
      ***
LAST
     1^C:\InterSystems\IRIS242\mgr\journal\20251029.003
EXPSIZE
     0
CURRENT
     1^C:\InterSystems\IRIS242\mgr\journal\20251029.003

Thanks for the correction.
I had something similar in mind, but didn't find the related doc!

So this means that the IF is not applicable in your context.
What commands are before the $$$TestIf(3) and after  ? 
I think of some  WRITE  $$$TestIf(3) .....    
Or you may try to explicitly write the macro-generated code to see any hidden issue
I'm running a bit out of fantas,y what may go on 

Strange.  It should generate   IF (3>0) {QUIT 5} and accept it.
Could you pls simplify the case for testing to 

#define TestIf(%arr) if %arr>0 QUIT 5

Not yet Halloween, but this looks spooky:
For me, all variants work: 
My versions:
InterSystems Studio Client  2024.1.0 Build 262
Server IRIS for Windows (x86-64) 2024.3 (Build 217U)

Now it's clear   instead of   (%arr > 0)  you simply should write (%arr>0)  
The ObjectScript compiler is interpreting the blank after %arr as an argument terminator

(error on compiling within a class) like: 
#define TestIf(%arr)        if (%arr > 0) { QUIT 5 }    ; no final dot.

#define is an element of ObjectScript
so it has to be embedded in a [Class]Method 
and it is only available within that method

It can't be flying free inside a class definition.

If you need your $$$TestIf(...)  in more than 1 method, you can deposit
it in some TestIf.INC  and include it BEFORE the Class statement !!
Then it is visible to ALL methods.

Attention: You can INCLUDE just 1 single  *.INC in a class definition.
If you need more than 1, you have to cascade it with #include  in  the first *.inc

Include TestIf

Class A.PERSON1 Extends %Library.Persistent
{
Parameter GlobalName = "^.........!"  ;;
/// .......
ClassMethod michael(param) as %Integer
{
    $$$TestIf(param)
 .........
    quit $$$OK
}

The AI example is misleading anyhow, as it just does a $O loop without any action to be done 
*.inc is typically kind of text generation code during compilation. 
What is your expectation for using the *.inc ?

%in and %gn are just text replacement parameters:
%gn is used as globalname, %in as first level subscript

If you just see pre you may have a problem with your  &html< ........>  sequence
that translates to write ........,! including all quoting requirements,

while <pre> any text </pre>  is just straight HTML

and  #(variable)# is a CSP instruction to display the actual content of a variable
and avoid any extra spaces

this may help to get the plain %request object:

k ^SPOOL s %io=$I O 2 u 2 ZW %request c 2 u %io

or whatever object you need to trace

YEAH, it's built for visual CSP pages

From Class Docs.:

Somewhere in the CSP page. This is just ~20% of the content

There are geographies in this world where a Decimal-Comma is used instead of a Decimal-Point.
Never met a Decimal-Pipe  😉