Repeating variables not set when index is a variable

Issue report by Hector Gil

Product

FileMaker Pro

Version

12 advanced

Operating system version

Windows 7

Description of the issue

When assigning values to a repeating variable using variables for the index FM assumes the variable is not repeating thus ignoring the index.

Steps to reproduce the problem

The following works:
Set Variable [$$M[1]; Value:1]
Set Variable [$$M[2]; Value:2]
.
.
Set Variable [$$M[9]; Value:9]


The following does not works:
$idxName = 1
$idxLabel = 2
$idxIcon = 9
Set Variable [$$M[$idxName]; Value:1]
Set Variable [$$M[$idxLabel]; Value:2]
.
.
Set Variable [$$M[$idxIcon]; Value:9]

Expected result

Obviously 9 differnt repetitions 1 through 9 for variable $$M, that is $$M[1] = 1; $$M[2] = 2 ... $$M[9] = 9

Actual result

Each value is assigned to the variable $$M replacing the last value, No repetitions, just $$M with the last value assigned.