Kiwi has three size recommenders, and they work differently. Which one you have decides which settings apply — so identifying yours is the right first step whenever something isn't working as expected.
The three recommenders
Basic Apparel Recommender. Your customer enters their own measurements. Everything is worked out in their browser. Chest and waist columns are optional, and cross tables are supported.
Advanced Size Recommender. Your customer enters height, weight and age instead, across several screens, and their measurements are estimated for them. Needs product information, a linked measurement for every column, and units. A chest column is required for tops and a waist column for bottoms — without them nothing appears at all.
Custom Size Recommender. You build your own steps and formulas. None of the sizing settings apply.
Quickest way to tell them apart
Look at what the first screen asks for:
Height and weight → Advanced Size Recommender
Body measurements on a single screen → Basic Apparel Recommender
Switching between recommenders
Switching between size recommenders will change your recommendations, even on the same chart. They score differently — Advanced estimates a body where Basic takes one directly. Neither is more correct. Advanced asks less of your customer; Basic is more predictable.