Originally posted in cdnusers.org by andrewjw
This is what's known as a "roundoff" error - in 15.2, 15.5 and 15.5.1 these sort of errors are common, less so in 15.5.1 as the code is improved here. The roundoff errors should mainly be fixed in 15.7, which is due in the next month or 2.
The workaround, as Randy R mentioned, is to add a oversize value to the shape - it's better to add the oversize value to individual shapes ratrher than as a Global Dynamic Shape Parameter. The oversize can also be added to individual elements - vias, pins etc.
One last word here - it's a good idea to work with the latest HotFix of the tools - this has improved code for dynamic shapes which should result in less errors.