Menus disappear in Lightning/Chrome/Macintosh (non High Sierra):

I am having the same issue as the people in this post: https://success.salesforce.com/answers?id=9063A000000eCMlQAM

Is there a Known Issue for this? If I'm the developer/admin for our Lightning implementation and I'm having this issue, this can't be something I'd want our actual users to experience.

Thanks!