Weights not adding together

Hi there

I have installed your plugin and set up my first table rate. I want to offer shipping cost by weight. I have given two products a weight of 10. (https://woollygoodstuff.co.uk/product/fingerless-gloves-merino-cashmere-silk/ and https://woollygoodstuff.co.uk/product/merino-silk-fingerless-gloves-black/). If a customer buys one of these, then I want to charge ￡1.90. If two are bought, ￡3.60. My settings are:
min value 6, max value 11, price ￡1.90
min value 12, max value 100, price ￡3.60

If I have one product in my basket the price shows as ￡1.90, but if I have two, it also shows as ￡1.90, not ￡3.60. It would seem that the two weights are not being added together.

I have another product covered by the same rule where the weight is 20, and that shows the correct prict of ￡3.60.

Can you help me to resolve this please?

Thank you.

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