This should be fixed in the 6.0.5 release this week. However, it's not a bad idea to specify the probe assemblies to speed up application startup. You do this by calling the CompositionHost:
using IdeaBlade.Core.Composition;
CompositionHost.SearchPatterns.Clear();
CompositionHost.SearchPatterns.Add("DomainModel.dll"); // Add whatever assemblies you need probed