Could reproduce but I can’t understand. Substring did throw an error when I used getslice and tried the Filename->Substring combo, I got an error at first, that I can’t reproduce at the moment, and then it ran smoothly, but with the for region still failing to output any strings.
Strange one indeed. Looking at the XML of the foreach region (Ctrl+C in patch, Ctrl+V in any text editor) it seems there’s a Keep pin we don’t see in the UI. Re-creating that pin and the loop starts working again. The system should probably get rid of such artifacts. Thanks for pointing it out.