Rare. Most parcels described as seized are actually held — stuck at a checkpoint, waiting on paperwork, or refused by the courier — and those usually move.
Telling the three apart decides what you do.
Held at a checkpoint
Interstate movement, a scan, a queue. The tracking stops updating and nothing is wrong.
What to do: wait, then ask. A few days of silence is normal. Beyond that the store raises it with the courier — they booked it, so they have the account and the reference. Tracking says delivered but nothing arrived
Refused by the courier
The parcel contained something the carrier will not take. Liquids, batteries, aerosols, blades and perishables are the usual ones, and a courier's refusal list is longer than the law's.
What to do: the seller gets it back, you get refunded. That is a cancellation rather than a seizure, and it is the seller's problem to solve — by posting it differently or not at all. How to pack an order
Actually seized
Something authorities have taken because it should not have been in the post. Genuinely uncommon, and it means the item was something that should never have been listed.
What to do: raise it from the order. You are refunded; you were not the one who posted a prohibited thing. The item does not come back, and that is not your loss to carry.
Where the item was prohibited, the store has a problem well beyond the order. Prohibited items explained
How to tell which you have
The tracking. A held parcel still shows a location; a refused one often shows a return leg beginning.
Ask the store. They can see the courier's side, and a straight answer is easy to give.
The item itself. If what you bought is on the awkward list, a refusal is far more likely than a seizure.
What is protected
All three end the same way for you: you are not out of pocket. The money is held until the item reaches you, so a parcel that never arrives is refunded. How buyer protection works
What you do not get is the item, and in the seized case nobody does.
For sellers
Check the courier's restricted list before you list, not after you sell. A refusal costs you the sale, the postage and a mark on your record, and all of it was knowable in advance.
Declare contents honestly. A parcel described as something else to get it carried is how a refusal becomes a seizure. Why is a light thing costing so much to post?
More: prohibited items explained, tracking says delivered but nothing arrived, what if my item never arrives.