You don't have your indicator on for if links are missing
Go to Panel Options
It's the flyout with the 3 lines on top of the Links Panel
Make sure 'Status' is selected
You will see an icon with a Triangle
And if your links are missing/modified you'll get a red or yellow warning symbol.
You cannot see it in your screenshot on your first post.
You'll need to adjust the width of your links panel - or adjust the column widths in the links panel - so the Status Icon is visible as I have shown.
Ah, thanks so much, I had expanded the width of the panel substantially but not sufficiently - I had no idea that the column width could inadvertently become so wide and, therefore, could not figure where the warning symbols had gone.
Great - glad it's sorted!