Design system color variables sometimes not appearing in colour dropdown

My team and I are experiencing a frustrating issue with Figma's handling of color variables from our design system library. While we have no problems accessing and using styles, color variables are extremely unreliable. In some frames, Figma correctly lists and displays the variables, while in others, it fails to recognize them, even when the colors are actively used within the file. This inconsistency occurs across multiple team members' Figma accounts. We've searched for similar reports but haven't found a solution. Any advice on how to resolve this would be greatly appreciated.