Plaintextgen generator is not being triggered within the multi stage generation plan

I've been working through the steps outlined in this tutorial: https://www.f1re.io/multi-generators  along with its corresponding repository: https://github.com/f1re-nl/mps-multi-generator-target 

I extended the functionality by introducing an extra generator language designed to produce a CSV file using the plaintextgen plugin. However, I've encountered an issue: the plaintextgen generator doesn't seem to activate when I click on "Preview Generated Text." Strangely, it only triggers when the "Generate CSV" enabler is present exclusively.

Any insights or suggestions on how to address this?