Its a PITA.
Some buyers claim they never received stuff that they did, or that it was damaged or the box was empty, or complain about shipping delays to try to get a refund, or even threaten to write a bad review, etc, if they don't get what they want. (Blackmail essentially)
Because some sellers are just as bad, they don't ship, or they ship but they don't package well, and stuff arrives broken/missing, etc...or its the wrong stuff, etc...the buyers feel like its a war.
In the US, when I drop something to be shipped, being old fashioned, I go to the post office or to fedex, etc...so I get the tracking info at the time I drop the shipment.
Many sellers print the label at home, but may not get to the post office that day...maybe the next, etc...and some its a week or more later, and so forth.
When the label is printed, the status shows differently than if its at a shipping hub, etc.
Until the status updates to show it was received at the first shipping point, the package MIGHT be still at the guy's house/business, etc.
So, everyone is nervous/leery about this sort of thing...and if they don't KNOW YOU, and that you'd never rip them off, they CAN panic, and then feel buyer's remorse, etc.
That goes for buyers and sellers alike.
I know your issues will clear up, but don't expect that your buyers will now only include happy campers. You could also simply explain the shipping situation before closing the deal...so there's no expectation that they get things sooner.
