A size is ruled out when any one of its measurements is impossible for the body. If every size is ruled out, the shopper sees the no-result message from the size recommender. Work through the causes below — they are listed most common first.
Stretch is set to zero
With no stretch allowance, any body larger than the garment measurement is ruled out immediately. This is correct for a stable woven fabric, but wrong for jersey, swimwear, activewear, or anything with give.
Raise the Stretch Factor slider to a realistic percentage for the fabric to allow those sizes back into the results. Only the Basic recommender's slider goes down to 0%; the Advanced recommender's stops at 10%.
Half measurements linked as full
If your chart lists flat, laid-out measurements, you must link the half variant of the measurement: in the Advanced recommender, open the Measurement selection dialog and choose Length only (1/2 of circumference) instead of Circumference. Linking a flat measurement as a full circumference makes the garment read at half its real size — so nothing fits.
Filter Oversized is switched on
The Filter Oversized setting (Basic recommender only, found per field under Intended Body or Product Measurement) rules out sizes that are much too big. This can empty the results entirely for smaller shoppers. If you are seeing no results for customers at the smaller end, check whether this setting is on.
The chart does not cover that body
If none of the above apply, compare the shopper's measurements against your largest and smallest rows by hand. If their measurements fall outside the range your size chart covers, no size will be recommended regardless of other settings.