Hi,
I'm having some issues with multi-item provider stations, I used stack filtering inserters and set them to filter mode (similar to LTN) and hooked them with the *-1 combinator like in the example blueprints.
They basicly work, but sometims have leftover cargo in the inserter hands, which might be the wrong cargo for the next delivery. How to solve that?

Tick "inactivity condition" on the cybernetic combinator. This makes the train wait for 1 second of inactivity even after the order gets filled , ensuring inserters have time to empty their hands.

I could've sworn I read about this on the mod page somewhere, but I can't for the life of me find it now.

e: you may also have to use the "locked item slots per cargo wagon" signal to make sure the wagons don't fill up completely, I'm not sure

Tick "inactivity condition" on the cybernetic combinator. This makes the train wait for 1 second of inactivity even after the order gets filled , ensuring inserters have time to empty their hands.

I could've sworn I read about this on the mod page somewhere, but I can't for the life of me find it now.

e: you may also have to use the "locked item slots per cargo wagon" signal to make sure the wagons don't fill up completely, I'm not sure

Not OP but i have to say that i do everything you listed and i'm still getting items stuck.

I've noticed the same thing. The inactivity condition fixes the failure mode where the train leaves because it's order has been fulfilled and some inserters still have items they intended to deliver, but now have no wagon to place them in.

There's another failure mode where the order completely fills the wagon, and the inserters have nowhere to put their items because the wagon is full, not because it left.

This can happen any time there are multiple inserters working on the same wagon (which if you care about speed is always), or when an inserter has a stack size greater than 1 (which again, if you're not at the very beginning of the tech tree, is always).

The easiest way to deal with this is to ensure that each inserter only transfers one item type. This is not optimal for speed, but it's easy and reliable.

The only other method I've found is to use combinators to keep track of the number of required items, then on each subsequent inserter, run the signal through an arithmetic combinator and subtract 12 (the max stack inserter stack size) from the total. This way, when a lot is required, all inserters will be working, but as the count nears the storage limit inserters shut off until only one is working. That last one also needs it's stack size to be set by a signal so that it only inserts exactly the required amount on the last swing.