What is the Mandarin equivalent of 唔夾 in Cantonese (i.e., not complementary)?
'People being incompatible' is 唔夾 or 合唔來 in Cantonese and  合不來 or 不合 in Mandarin

These two people have always been incompatible with each other
佢哋兩個一向唔夾 (Cantonese)
他們二人一向合不來 (Mandarin)
他們二人向來不合 (Mandarin)

'Things being incompatible' in Cantonese can also be 唔夾, and 不般配 in Mandarin.

Chinese medicine and Western medicine are incompatible
中藥同西藥唔夾 (Cantonese)
中藥跟西藥不般配 (Mandarin)