Error message: impossible to get 1 item of missing value (can't open Word files in Word 2016 with Automator)

When I test in Automator my process to Find & Replace text in multiple word files I receive the error message in the title. It seems that Automator can't open the files (I use Word Office 2016).

Here's my process (mine are in French so I'm translating):

Get specified folder items (to access the files)

Obtain folder content (because someone said to use this)

Open Word files

Find & Replace

Find & Replace

Find & Replace (the number of times needed to find & replace multiple lines)

Save file

Close file

I can see that the script gets the files, obtains the content, but fails at the Open Word files (that's when I get the error of impossible to obtain item 1 of missing value, and of course no files show up in the results panel for this part of the script.

Please help if there's a way around this. I tried opening the files in Word before running the script and using this process:

Get specified folder items (to access the files)

insert content to Word file (replace content selected)

Find & Replace

Find & Replace

Find & Replace (the number of times needed to find & replace multiple lines)

Save file

Close file

But it didn't work (and I didn't think it would, but they linked together, so I hoped so).

I'm in Automator Version 2.6 (419) & El Capitan OS X Version 10.11.6 (15G31)