Why is R's officer/officedown moving my header down to the bottom of the page?

I only have one "heading 1" and yet it's at the bottom acting like it's the second header. Is there something I'm not aware of?

Code with example data:

library(flextable)
library(dplyr)
library(officer)
library(officedown)

df <- data.frame(text_level = c(1, 4, 2, 4, 3, 4),
                 text_style = c("heading 1", "Normal", "heading 2", "Normal", "heading 3", "Normal"),
                 text_value = c("Section 1", "Lorem ipsum.", "Section 1.1", "Lorem ipsum.", "Section 1.1.1", "Lorem ipsum."))

doc <- read_docx()
# body_add_par(doc, value = "Hello World!", style = "Normal")
# body_add_par(doc, value = "Salut Bretons!", style = "centered")
for (i in 1:nrow(df)) 
{
  text_value <- as.character(df[i,'text_value'])
  text_style <- as.character(df[i,'text_style'])
  body_add_par(doc, value = text_value, style = text_style)
}
print(doc, target = "example.docx")

The issue is that when adding new paragraphs you have to assign the result back to doc.

library(officer)

df <- data.frame(
  text_level = c(1, 4, 2, 4, 3, 4),
  text_style = c("heading 1", "Normal", "heading 2", "Normal", "heading 3", "Normal"),
  text_value = c("Section 1", "Lorem ipsum.", "Section 1.1", "Lorem ipsum.", "Section 1.1.1", "Lorem ipsum.")
)

doc <- read_docx()
for (i in seq_len(nrow(df)))
{
  text_value <- df[i, "text_value", drop = TRUE]
  text_style <- df[i, "text_style", drop = TRUE]
  doc <- body_add_par(doc, value = text_value, style = text_style)
}
print(doc, target = "example.docx")