Hello,

I got an error when debugging the behaviour of a formula.

You'll need:

(setq org-table-formula-debug t)

Then with any luck this should allow you to reproduce the error: C-c C-c to run formula.

| Task                  | Estimated Effort |
|-----------------------+------------------|
| INTRODUCTION          | 9:30             |
|-----------------------+------------------|
| BACKGROUND            |                  |
|-----------------------+------------------|
| FOO WORKFLOW          |                  |
|-----------------------+------------------|
| BAR WORKFLOW          |                  |
|-----------------------+------------------|
| BAZ WORKFLOW          |                  |
|-----------------------+------------------|
| ADDITIONAL WORKFLOWS  | 1d 4h 0min       |
|-----------------------+------------------|
| FINDINGS              |                  |
|-----------------------+------------------|
| ADDITIONAL ANALYSIS   | 24:00            |
|-----------------------+------------------|
| DISCUSSION            |                  |
|-----------------------+------------------|
| BIBLIOGRAPHY          |                  |
|-----------------------+------------------|
| Appendix: Status      |                  |
| TOTAL WORKDAYS NEEDED | 5d 5h 30min      |
#+TBLFM: @>$2='(org-duration-from-minutes (apply '+ (map 'list 'org-duration-to-minutes (list @I+1$2 @II+1$2 @III+1$2 @IIII+1$2 @IIIII+1$2 @IIIIII+1$2 @IIIIIII+1$2 @IIIIIIII+1$2))))

I've attached a patch that fixes the problem for me.

I'm on Org mode version 9.1.14 (release_9.1.14-974-ga85ba9 @ /Users/joe/org-mode/lisp/)

Joe