That’s what Chris Bryant seems to be saying too. I think the plan was that the Tories would vote down the Labour amendment, which would then be followed by the SNP motion and if that failed the government amendment. The wheels came off when it became clear that the Tories didn’t have the votes to vote down the Labour amendment or to get their amendment passed.
They then seem to have forced a procedural division right at the last minute and walked slowly through the division chambers because they were under the impression that the motion would fail if it wasn’t sorted by 7pm. Unfortunately for them the standing orders say that the vote can take place after 7pm under certain circumstances.