One of the down sides of having your program link directly to a website for help by default. Probably the issue you are searching for has not been updated since the help file (chm) on your hard drive was created, so it should still be available there.
"Both the offline and the online version of SONAR X3's documentation has been updated to include new topics pertaining to SONAR X3d as well as numerous corrections from user feedback.
We recommend clearing your browser's cache if any new topics are not displaying for you. You can also press F5 to refresh the current page you are on. The offline .chm version has been updated as well. No action is necessary for those changes. If you prefer the offline .chm version, you can set F1 to open it by default by going to Edit > Preferences > File - Advanced and selecting "Always Use Offline Help".