You appear to be mixing ordinary Inventor assembly-management tools with Frame Generator.
In your browser, you can see the Frame assembly has been mirrored (green arrow). There is also another frame assembly that has been copied and mirrored. Assuming they all come from the same layout, the assembly structure will fail at some point because you are breaking the structure required for the frame generator tools.

Frame Generator assemblies need the following structure:
- Parent assembly
- Layout component
- Frame assembly (and "Reference Skeleton") are created automatically by Inventor. The Frame assembly should never be treated as a "regular" subassembly because it needs to maintain the above structure, or it will break.)
- Frame members

If you need to copy or mirror a Frame Generator assembly, create a NEW assembly, place the assembly (1) above into that assembly and mirror/copy it there. This will preserve the structure (1 > 2 > 3 > 4) required, and you won't break the relationship between layout and frame assembly.
It is a very robust workflow providing you don't break the 1 > 2 > 3 > 4 structure.
Peter