I would be willing to bet that there are several vehicles on all of the ships that won't trigger VIN allocations during their respective crossings, but will be matched to orders at random points when ships have docked/unloaded/cars delivered to centres across the UK.
Tesla simply are not organised enough to have a 100% coverage across all outstanding orders whilst ships have not even got to Zebrugge, let alone the UK.
Anyone who ordered a while ago i.e. Aug/Sep/Oct/Nov/Dec 2019 - don't give up hope for a random text in the next week or so.
Feel better now ? You are welcome