fillMergedCells = TRUE doesn't work

[telenskyt]

Describe the bug
fillMergedCells = TRUE doesn't actually work.

To Reproduce

library(openxlsx)

sek_f <- "d:/tomas/bug_openxlsx.xlsx" 

w1 <- loadWorkbook(sek_f)
names(w1)
sek_hdr <- readWorkbook(w1, sheet = 1, colNames = FALSE, rows = 1:2, fillMergedCells = TRUE)
sek_hdr

Expected behavior

      X1   X2     X3   X4
1 group1 group1 group2 group2
2   col1 col2   col3 col4

Actual behavior

      X1   X2     X3   X4
1 group1 <NA> group2 <NA>
2   col1 col2   col3 col4

Screenshots
If applicable, add screenshots to help explain your problem.

Example files

bug_openxlsx.xlsx

Additional context
I have seen issues here that report the same problem - #6, #318 , they don't seem really resolved, have tag "Stale", why is it still not in open issues when it is not truly resolved?

[JanMarvin]

Hi @telenskyt ,

the package is no longer actively developed. Please have a look if openxlsx2 or readxl solve the issue.

[telenskyt]

@JanMarvin thanks for the info! I had no idea!! Why don't you just say so in the package profile? The latest release date 2025-10-31 makes people think this package is actively developed! (This is what I am usually checking). Thanks.

[JanMarvin]

There’s is a note in the package readme, but maybe we should add it to the NEWS file too. As stated, there is no urgent requirement to change a thing if one is happy with the previous state of openxlsx, this won’t go away. But new development, at least from my side, is happening in openxlsx2.

library(openxlsx2)

sek_f <- "https://github.com/user-attachments/files/24338427/bug_openxlsx.xlsx"
w1    <- openxlsx2::wb_load(sek_f)
sheet <- openxlsx2::wb_get_sheet_names(w1)

# read_xlsx and wb_read are wrappers for wb_to_df()
sek_hdr <- openxlsx2::read_xlsx(
  w1,
  sheet = sheet,
  col_names = FALSE,
  rows = 1:2,
  fill_merged_cells = TRUE
)
sek_hdr
#>        A      B      C      D
#> 1 group1 group1 group2 group2
#> 2   col1   col2   col3   col4