Wire to rope splice, advice required.....

[Robbie.g]

Hello collective fonts.
Need some advice.. having trouble with the wires' core pushing out between the tucked bundles. This was an intermittent problem on 10mm - 5mm wire / 12mm - 6mm, the 'normal' combinations!? But today was given 12mm to 5mm wire, and despite all my best efforts to have all rope bundles having the same number of yarns, the same tension on all bundles the core 'yarns' on the wire still lifted through.. In all other respects the splice looks great except this... How frustrating
So i'm picking that there is obviously something wrong with my technique... need some pointers.
Any advice would be really appreciated.
Thanks in advance