If the caret package is loaded, bal.tab() with the cluster option will fail. For example,
library(cobalt)
library(caret)
bal.tab(vs ~ mpg, data = mtcars, cluster = "am")
Error in UseMethod("as.cluster") :
no applicable method for 'as.cluster' applied to an object of class "data.frame"
If the caret package is loaded, bal.tab() with the cluster option will fail. For example,