Why does Illustrator outline text when I use saved artwork from my library?

If you place an Illustrator file from a CC library as Linked, you actually place a PDF representation of that file.

If you later embed that pdf object, you can get these problems, all the Illustrator editability is gone.

If you place the file as  a Copy, you will place the  editable Illustrator content.

You can also double click the item in the Library, copy the content and paste it into a new file.

If you don't want some of the text to be forced into being outlined you need to make sure all the fonts are embedded in the PDF. If you save your PDF with Preserve Illustrator editing capability checked (turned on) you should be able to open the PDF in Illustrator without loosing or outlining fonts. This may also depend if you have all the fonts loaded in your OS when you open the PDF. If it's a really old .ai file there may be compatability issues moving the file into the current illustrator text engine. I'm just throwing ideas out because we don't have access to the files in question. 

Generally if you have some text which is outlined and some which is live type there will be a slight type weight difference between them. You can thwart this by selecting the live type and applying the Effect > Path> Outline Object to the text. Understanding then if you save a PDF from this illustrator file all the type with this Effect applied will be forced to outlines in the PDF. In which case always best to keep a native .ai file for the editing of the live text.

Hello @Jennifer376183986htq,

Thanks for reaching out. Would you mind confirming if the icons were saved as a PDF? Also, kindly share a public link to a sample file after uploading it to Dropbox/Google Drive/etc., so we can check it on our end.