Qt Quick Compiler fails to compile array

https://www.qt.io/blog/compiling-qml-to-c-a-4x-speedup

Attempting to recreate this program in 6.8.2 on windows renders the following errors:

C:\Users\dadehnel\Downloads\CompilerEval\Categorizer.qml:24: warning: Could not compile binding for numbers: Cannot generate efficient code for storing an array in a non-sequence type [compiler]

Categorizer.qml:39: warning: Could not compile function sum: Cannot generate efficient code for LoadElement on a sequence potentially affected by side effects [compiler]

Categorizer.qml:59: warning: Could not compile binding for onCompleted: Cannot generate efficient code for LoadElement on a sequence potentially affected by side effects [compiler]

Due to this the performance gains referenced in the blog post are not seen. Did something change with the compiler between 6.5 and 6.8? Is this expected behavior? I believe specifically the line referring to
        var result = [];
Is what is causing the issue