Row standardization works by dividing the sum of all weights for the neighbors of a feature by the total number of neighbors. When there are no neighbors, the result is a zero divide (unstable). All features need at least one neighbor when the row standardization option is selected.
Choose a Conceptualization of Spatial Relationships option and appropriate parameters (for example, a larger distance band or threshold distance) that will ensure every feature has at least one neighbor. Alternatively, create a spatial weights matrix file using the Generate Spatial Weights Matrix tool; set the Number of Neighbors parameter to an integer value greater than or equal to 1.