From what I can figure out, they are canceling trains simply because there’s not enough room in the station for all the trains. They are so far backlogged that they just have to occasionally cancel trying to keep things moving. They’re running 2 to 3 hours behind and it starts to snowball on them.
I did look at the Brussels suggestion and it does work, but for me it would be about $200 more than the cheap airfare I got.
It’s an unbelievable mess, and particular bad for those people who wanted to do a day trip to or from London/Paris
It’s also a cautionary tale for people like me who tend to book unprotected connections and have to juggle. Paying attention what going on going on and being willing to spend money to get where you need to do is required if you do What I do. If that was not something I could handle, I should have booked my flight out of Paris instead of going back to London.