Ivan - thanks for your question. I am going to move this to the product-specific Xpedition community where the topic is more appropriate and it will receive greater visibility. The Member Resources area is for overall community questions and suggestions.
Try to run TOOL -> CES diagnostic and after click to report to resolve errors
It might be zero row heights, reset them with: View → Reset Row Heights
Hi guys thanks for the feedback.
I managed with some help to get to the root of my problem.
It was just an issue of incorrect Filter settings ... the correct filter settings needed to be as follows
Filters -> Levels -> All
Now that I have made the correct filter settings I can again see and modify clearances.
Thanks for your support and good day.