This route is huge. When you say it ‘jams’ I’d suggest you simply ran out of patience :-). It takes a long time to complete the saving sequence.
The ECML merge *does* work but will always be tricky due to its size, I think. I have actually made a scenario for it called 1E01, which you may or may not know, runs a fast service from EDB to KGX. Sometimes I can’t get it to load before the dreaded OOM crash. Other times it does!
Good luck, Dom.
