Bottom line is avoid [fcfps12m.s]. Instead use [fcfps12mq1d.s] or [fcfpsy1.s]. Details:

FCF is adjusted both by the company and the data vendor. FCF per share:

Ticker  Barchart   M*   SIPnew  SIPold  period
  BAX     2.04    2.04   0.89    0.89    Y2023
  MMM     9.14    9.15   3.17    3.17    Y2023
 AMZN     1.12    0.73   0.49    0.72   Q202406

I do not know how [fcfps12m.s] is calculated and so would avoid using it. For example, both BAX and MMM have fiscal year ending December 31st, and latest reported quarter ending September 30, 2024. [fcfps12mq1d.s] is the sum of quarters 1 through 4 as expected. Somehow, [fcfps12m.s] is more negative than any combination of quarters.

Ticker  fcfps12mq1d.s  fcfpsy1.s  fcfps12m.s  fcfpsq1.s  fcfpsq2.s  fcfpsq3.s  fcfpsq4.s  fcfpsq5.s  fcfpsq6.s  fcfpsq7.s  fcfpsq8.s  perendy1.s  perendq1.s  diff
  BAX       1.04         0.89       -0.38       0.41       0.08       0.33       0.22       -0.03      0.00       -0.14      0.63       25889       26077     188
  MMM       2.80         3.17       -3.06       1.22       0.55       -0.05      1.08       0.43       -0.18      -0.46      1.05       25889       26077     188

============
For 2024Q3, SIP reports for MMM:
Cash from Operations: $(1.8) B
Cap Ex: 0.246 B
FCFPS: $1.22
FCF: 0.55 B shares * 1.22 = $0.67 B

SIP is reporting the adjusted FCF, discounting some of the adjustment.

3M Reports Third-Quarter Results
Adjusted free cash flow of $1.5 billion.
Cash from operations of $(1.8) billion, driven by $3.6 billion net after tax payments for costs of significant litigation, primarily Public Water Systems and Combat Arms Earplugs.
investors.3m.com - Quarterly earnings

========= Some FCF numbers ========

Y1 BAX:
Barchart: $1.034 B
M*: $1.03 B
0.506 B shares

Y1 MMM:
Barchart: $5.065 B
M*: $5.07 B
0.5539 B shares

FCF for Amazon in the quarter ending June 30, 2024:
Barchart: $11.725 B
M*: $7.66 B
10.477 B shares

New SIP data and AMZN
"To see what might have changed with the new data source, I looked at what SIP reports as AMZN financial statements for the quarter ending June 30, 2024. FCF might be the most significant change."
field: 20240927 data, 20241001 data
Free Cash Flow per Share: 0.72, 0.49
lizgdal writes on New SIP data and AMZN