Windows 10: PDF and DOCX miniatures not showing

Hello all.
First of all : Windows 10 Family; V 1903; Date 7/10/2019; System expl. 18362.1139
Secondly: Can anyone help me with this irritating problem that I've been trying to resolve for a while.
That is to say, certain PDF and DOCX files refuse to show their miniatures in Explorer giving different results depending on where you view the file.
To add insult to injury, sometimes the PDF file miniatures show for a while then go back to the Adobe icon.....but not all of them.
I have over the last week or so tried various solutions and am certain that all the correct boxes have been ticked (or unticked) :
Explorer - Do not show miniature (unticked)
Adobe - Show miniatures (ticked)
Word - Save with miniature (ticked)
I've run all I can in the way of 'repair program' for each.
I've reset default settings wherever possible.
Plus various over solutions that haven't made a difference.
I've joined an image that show that, curiously, in the Quick Access folder some files are in miniature, some aren't but in all cases if I go to the home folder for the file the miniature is not shown.
Its a mystery to me.
I thank you all in advance for any help and suggestions you might bring to this particular table.

:)

 

Showing epub, mobi, djvu, azw3 miniature previews in windows explorer

I've already answered that, I believe.

I think you're referring to the preview pane, which you show like this:




I said

I will expand that for you to try to make it clearer.

a. Windows does not natively include code to display the content of all possible file types in the preview pane.
b. To be able to display files not native to Windows there, you need extra code
c. That code is called a preview handler.
d. To show the content of those extra file types you need to install a program that provides that code.

Here are the preview handlers I have on mine:

You will see Sumatra listed there. You will note it is listed for pdf. It is not listed for the file types you mention. Why? Because it does not provide preview handlers for them.

 

File extension *.docx

I already did all the steps you suggested but MS Office 2013 ignored my change and defaulted to *.docx. Is there some other solution?

 

Best free PDF software?

I use:

• UnityPDF to merge/split PDFs and to insert/extract pages

• doPDF to create PDFs from any program that is capable of printing

• Foxit Reader to view PDFs and to type in them