Could you indicate which Oxygen version you are using?
If you are not using Oxygen 23.1, could you try on it?
If you reproduce the problem on the last version, is it possible for you to provide a sample with at least a DITA Topic and an SVG file.
Make sure no sensitive information is contained in the samples.
You can send the sample directly at email@example.com
Having trouble installing <oXygen/>? Got a bug to report? Post it all here.