Please send your design to SupportNet, they should be able to assist.
You need to remove the unused Multicore ID's from both cutback nodes manually.
the twin twist are not on the cut back nodes. They are shown in the left box to be added to the cut back node but not in the right one as added to cut back node.
They are likely referred to either by a wire or by another cut-back node, which you will have to find and delete manually.
Easy way to find it is to switch on "Show all multicore cut back nodes" and there was one node showing them.
Removed them and its OK now.