Non-breaking spaces and full stops!

I've been using Word since the 1980s and not had this until recently! Looking through my latest Word document, on virtually every single occasion I have put in a full stop, followed by two spaces before starting the next sentence, the system has put in the two spaces but marked the second one with that non-breaking-space symbol. Apart from once as it happens, for whatever bizarre reason! But, just like you, when I try out a new document and do the same thing, everything is normal... So I can't reproduce it. Hence I returned to the original, offending document, to put in some more sentences, and it behaves as it should (aggggh! ie no non-breaking spaces inserted automatically)...

Very confusing... In normal circumstances, to insert a non-breaking space, I highlight the space, then use control shift enter to get what I want. So I just don't see how, in a very large document I've put together, so many non-breaking spaces have appeared simply by inserting two spaces...

@Michael Harwood

Based on your description, I have some questions as below.

1. Do you use Word for Mac?
2. Does this issue occur on specific document and you could not reproduce it on other Word document?

If so, I think this may be related to the setting of the document.
You could try to copy the content of the “offending document” to a new document to check this issue.

If I have any misunderstanding or you have any updates, please let me know.

If an Answer is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

I'm using Microsoft Word for Mac, Version 16.45 (21011103).

It doesn't necessarily occur on other documents; indeed, it doesn't always occur even on this document!

I've just been writing: normality - ie I tap in two spaces after a full stop & no non-breaking space appears... I've then highlighted the single space between two words at the end of a line of text, hit 'Shift control' and the word drops, as expected to the next line. I've then used 'Shift option' and got the same result. Perhaps that's as it should be... Either way, having deliberately inserted that non-breaking space, I get a little symbol like a degree icon, to tell me I've done that. It baffles me, therefore, why have that symbol when I did NOT deliberately put it there.

Thanks for your interest; it's much appreciated. But I guess this is 'just one of those things' and there are more important things in life to worry about. If it wasn't for lockdown, I wouldn't be doing this inquiry work or wasting your time!

And what I can perhaps add is that 'the issue' arises when I copy and paste some text from an email into the same Word document. Indeed, when I do this, a non-breaking-space appears even between words, even when only a single space was entered... sometimes but not always. And I can see absolutely no logic in why it does and why it doesn't...