bug fixed: https://stackoverflow.com/questions/44360040/group-rows-function-in-kableextra-package-not-grouping-rows
diff --git a/R/add_indent.R b/R/add_indent.R
index 33ad6f7..3fc2837 100644
--- a/R/add_indent.R
+++ b/R/add_indent.R
@@ -38,7 +38,7 @@
   out <- kable_input
   for (i in positions) {
     rowtext <- table_info$contents[i + 1]
-    out <- sub(rowtext, latex_indent_unit(rowtext), out)
+    out <- sub(rowtext, latex_indent_unit(rowtext), out, perl = TRUE)
   }
   return(out)
 }