MAX 9: [gen.codebox~] buffer issue

Reading from a buffer in [gen.codebox~] dosen't work when using the attribute “index = ‘phase’”:
“dsp.gen: [string "-- main2.lua..."]:697: failed to compile genpatcher”

The same code inside of [codebox] within a regular [gen~] works just fine.

When clicking on “Edit” in the action menu of the [gen.codebox~] the [gen~] object inside is revealed, showing that the ‘phase’ attribute is not presented as a string.