If you select a clipping or folder (or make a new one), the text turns white to be visible with the selection color. If it's not selected, the text is black. When you hit return with a snippet selected, the text turns editable. While it's initially selected, with the macOS text selection color, the text is white. As soon as you start typing, the text is no longer selected, but the text remains white, and now there's no color at all behind it, so it's invisible. You just have to hope you don't make a typo while typing. While the text is actively being entered/edited, the text should be black so as to be visible.
If you select a clipping or folder (or make a new one), the text turns white to be visible with the selection color. If it's not selected, the text is black. When you hit return with a snippet selected, the text turns editable. While it's initially selected, with the macOS text selection color, the text is white. As soon as you start typing, the text is no longer selected, but the text remains white, and now there's no color at all behind it, so it's invisible. You just have to hope you don't make a typo while typing. While the text is actively being entered/edited, the text should be black so as to be visible.