Hello @Anonymous Thank you for posting to the forums.
Here are a few clarifying questions for you.
Are you able to reproduce this issue?
Does it happen with any file or a specific file?
Which version of Revit 2018 are you on? The newest is 2018.3.3 and can be accessed using the Autodesk Desktop App or manage.autodesk.com
Have you found the problem happens with any dimension type?
Would you be able to share a brief screencast of the problem.
https://knowledge.autodesk.com/community/screencast
When you are in the view and can see the dimensions, Have you tried copying them to clipboard, deleting them and pasting them back aligned to the same place in the Revit view?
Does this help to show the dimensions?