I had to save in word format cuz recipient couldn’t open odt and I’m now facing a bug where text color formatting resets after I close and open the document,
it happens for base style only, - I apply auto text color - it becomes my system color (orange), I save, I close it and open again - and it’s black again 
Libre 24.8.3.2 x64 + Win 10
for ODT format this worked properly, but not for DOCX
is not a valid version of LibreOffice.
24.8.3.2 then
You can upload a sample file with the problem here so someone can look at it and examine. Thank you.
Here, I can neither save “auto text color” on the text (which uses base style) itself nor on the base style it uses - it shows that it changes but after reloading the document it’s not saved but reset
example.docx (7.9 KB)
What are you calling “auto text color”? Is it setting in Tools>Options, LibreOffice>Application Colors, General Font Color?
And what is “base style”? Do you mean Default Paragraph Style, the paragraph style used everywhere? Or some formatting you applied over characters? Anything else?
and yes, default paragraph style
Not sure what Automatic exactly does. I suppose it is not simply OS colours. Contrast is also taken into account so that text remains visible even on unusual background.
Have you enabled a dark theme in your OS (though it does not look so)? There are problems with dark themes.
I played a bit with OS themes (Fedora Linux with KDE Plasma desktop; but I didn’t go to forcing “exotic” OS text colour). After save-reopen cycle, my text colour is the same as at save time.
The problem is not the color but that it does not get saved along with the document saving (for this document) after setting it for a text fragment or the text style
I have a high contrast win theme, here:
high_cont.zip (1.4 KB)
Not sure what Automatic exactly does.
it should be “default color” and “no color specified”, like how it is for the web and css