I have a document I created using Open Sans font. No problems until I was making my last round of corrections. I typed my content into the textbook in all lower case, then clicked on the Large Cap/Small Cap tool. The "I"s showed up as seriffed letters and did not reduce to the small cap size. Also, I noticed when I typed into a new text box in all caps, the I's were continuing to appear with Serifs on them. That was the only letter that did. I reloaded by font into font book, where the preview of the font shows up correctly. It was just not appearing in my document correctly. How does such a thing happen? Open Sans is a free downloadable font.
I appreaciate any insights anyone has to offer on this. I've never had that happen before in a font.
Open Sans is available from a Adobe fonts (fonts.adobe.com) as part of your Creative Cloud subscription (but you didn't say what verson of InDesign you're using). I tried the Adobe version of the Google-created font and it seems to work fine. You might uninstall the one you're using and switch to the Adobe version: