I am trying to plot variable importance from a support vector model using the vip package in R. However, the plot is empty.
set.seed(2022)
pet_uv_raw_svm_fit %>% 
extract_fit_parsnip() %>% 
vip(method = "permute",
  target = "class",
  metric = "accuracy",
  nsim = 20,
  pred_wrapper = kernlab::predict,
  train = pet_uv_train[, -1],
  )

With the same code but only different data, then I get a good variable importance plot.
set.seed(2022)
pet_uv_svm_fit %>% 
extract_fit_parsnip() %>% 
vip(method = "permute",
  target = "class",
  metric = "accuracy",
  nsim = 20,
  pred_wrapper = kernlab::predict,
  train = pet_uv_train[, -1],
  )

So, my question is what does an empty vip plot mean? and what is the reason causing the result?
Any idea is very much appreciated.