@joshuash beside what @Thyme is saying these things come to my mind:
- (especially) with nested loops it can make sense to use Metanodes in order to make sure what part of the loop will do what and how they are wired. You can check „select sope“ by right clicking on the Loop node and see how KNIME would interpret the wiring.
- it might very well be necessary to check the logic behind the loop and if it would work in every constellation. It might be necessary to provide a dummy table of the same structure at the end of a loop or try catch block (Try Catch 1, Try Catch 2)
- you could educate yourself abut loops with this collection or with @armingrudd articles
Example for the use of if and CASE nodes (with Python nodes but could be any other nodes also):