Yes, this does come up now and again, mostly from text that has been pasted in from some other editor. Here are a few threads:
It could be that the width of your text editor window is narrower than the indent setting itself, so all lines are wrapping whether they have an indent or not.
At any rate, I believe it is mentioned in these threads, but to get your manuscript fixed as quickly as possible: try selecting these paragraphs and dragging the right-indent marker on the ruler as far right as it will go. It will kind of “snap back” a bit if it worked. Now the lines should act like the rest. There is more detailed info in the links.