Have you managed to communicate with a real person rather than a chatbot?
Due to having multiple problems, I've found that once you get over the admittedly significant hurdle of finding a human, they can be very good at identifying the actual reason for missing parcels and solving the problem.
In the last few months I've had
Parcel destroyed so wouldn't even try to deliver
Parcel paused in the system for 2 weeks before eventually being delivered after having got wet and then repackaged by Evri (the contents were in a bag with their labels on). Fortunately this one was replaced by the sender as it was previously dry cat food so obviously unusable.
Multiple occasions where I got the 'out for delivery' message at least 3 days running only for parcel to never turn up.
Also tracking just stopping at out for delivery and nothing happening for days.
I think the problem is that the system has given the public the expectation that delivery is free or very cheap and no one will pay or charge what it really costs to provide a good service so corners are cut and the local couriers are exploited so it's impossible to make a decent living without doing very long hours, so the only ones who do it are those who are desperate enough to do it and/or don't stick at it very long so don't know rounds and where places are, don't feel incentivised to complete harder deliveries (heavier parcels, further away, having to deal with flats and intercoms etc) because they get pennies per parcel.