We are running WF3.0 M170 and actually came across the same problem. A flexible component can be used and will be shown in our BOM repeat region if it is only used as one component or in one pattern. If we use more instances, more patterns, different flexible dimensions, the line in our repeat region disappears, just like the BOM balloon. Our Software supplier took a look at it also and didn't have that problem on exactly the same assembly, ... just until they realized they were working with WF4 (don't know the datecode) We also tried this on a WF4 and also found that his problem is no longer an issue on WF4 !