OK, as it's left water above the filter it's not getting it out quick enough.
We've ruled out the drain connection as the point of restriction.
We've proved by aiming it into a bucket that it cannot get rid of the water fast enough to empty the machine in the alloted time.
This leaves us with the hose from the pump to the metering tank, the metering tank and the hose from the metering tank to the drain connection.
You'll now need to take the appliance out and take the panels off so you can see the metering tank (left side when viewed from the front).
Check the state of the metering tank, if it's blocked you'll need to strip it out and try to clean it out by backflushing with a garden hose or similar.
disconnect the hoses from the pump and to the drain, you'll have to improvise here to join them together.
Once joined, try filling and draining the dishwasher. If it drains ok it would suggest a restriction in the metering tank.
Sorry if it's getting a bit heavy on the work and testing but it's the only way to narrow it down. I've had these faults before and they can be a real pain to nail down.
When testing make sure the drain hose is as high as the top of the dishwasher. This will simulate the height the dishwasher has to pump normally.
Good luck with it.