If getting this error "not act on confirmation", must call acknowledgeTradeProtection
https://github.com/DoctorMcKay/node-steamcommunity/commit/a61b50b7a2c2d2e6baa8a6592d26f24a0656058e
For us, assetids not changed, all items after protection lock copied to context 2 with same assetid (and now have same items on context id 16 and 2 🙂)