Macro, Triggered from Hazel Rule, Fails with Error "CompileAppleScript string failed"

When I get a certain Hazel Rule Match on my Mac the same Hazel rule has a final action that starts an Applescript that calls a KM Macro. As below:

This works fine but only for an unpredictable number of iterations (I've seen 20 iterations work and later I've seen 150 work). Eventually it fails with the following errors. Any ideas as to why this fails? Thanks.

From the KM Engine Log:

2018-06-14 07:25:41 Launch Task /Applications/Keyboard Maestro string failed

From the Hazel Log:

2018-06-14 07:27:31.108 hazelworker[90747] [Error] AppleScript failed: Error executing AppleScript on file /Users/abbott/Desktop/344—QDI Historical Report.xlsx.

2018-06-14 07:27:31.109 hazelworker[90747] OSAScript error: {
NSLocalizedDescription = "Keyboard Maestro Engine got an error: AppleEvent timed out.";
NSLocalizedFailureReason = "AppleEvent timed out.";
OSAScriptErrorAppAddressKey = "<NSAppleEventDescriptor: [0x0,296e96c "Keyboard Maestro Engine"]>";
OSAScriptErrorAppNameKey = "Keyboard Maestro Engine";
OSAScriptErrorBriefMessageKey = "AppleEvent timed out.";
OSAScriptErrorMessageKey = "Keyboard Maestro Engine got an error: AppleEvent timed out.";
OSAScriptErrorNumberKey = "-1712";
OSAScriptErrorRangeKey = "NSRange: {0, 0}";

Here's another post with the same error message. Unfortunately this post is unresolved as well, but maybe @peternlewis can make sense of this.

The "CompileAppleScript string failed" is most probably talking about an AppleScript within an action within the executed macro, rather than the AppleScript shown in Hazel (note that the AppleScript is probably being used implicitly by Keyboard Maestro rather than an Execute AppleScript action, eg something like the SystemVolume token, which uses AppleScript to retrieve the value.

My guess would be the system running out of process ids, caused by too many executions of the CompileAppleScript tool in quick succession. (CompileAppleScript is a tool that Keyboard Maestro uses to execute AppleScript outside of the Keyboard Maestro Engine process to avoid the crashes that AppleScript periodically causes).

Peter, in that case, is it correct that you would NOT have to use the CompileAppleScript tool with a .scpt file, since it is already compiled? If so, the user could use a script from file with the Execute AppleScript Action.

No, Compile executes the AppleScript as well, it performs a variety of different internal AppleScript features for Keyboard Maestro related to off-boarding the AppleScript interaction to avoid crashes in AppleScript taking out the engine or editor.

I come across this issue almost every single day.

Launch Task /Applications/Keyboard Maestro string failed

I run a very long-time macro everyday, which sequentially execute other macros. It usually should take about 1.5 hours to finish all Execute Macro actions. And I found the whole keyboard maestro engine always freezes until I touch the Mac manually. Today it froze again, I looked at the Mac carefully. I touched the trackpad and it started to simulate scroll wheel, so I am pretty sure this issue happened during the opening web action group and may before simulate scrolling or simulate scroll itself. But I am not sure which action is related to Apple Script. Maybe Simulate Scroll Wheel?

It's so hard to reproduce. Only after running macro for long time, and it will appear somewhere in the middle. I have no idea which action it straightly relates in sure.

Background Information:
MacBook Air (13-inch, Mid 2013)
macOS Version 11.1 (20C69)
RAM 4 GB 1600 MHz DDR3
(an old Mac using as a "server" at home)
Keyboard Maestro Version 9.2