If you are experiencing Royal Mail tracking numbers not going up to Amazon (and other marketplaces), it could be that you are using services that aren't true tracked services.
These include Royal Mail 24 & 48 as well as some others
These services don't return a true tracking number, what you actually get is a Delivery Confirmation Number (DCN) which is really for you as a seller to prove it was delivered. They may or may not get intermediate scans before delivery. As this is a free service provided by Royal Mail, no scans are guaranteed. So it may not be accepted by Amazon (and possibly eBay) and you may get penalised, this is why we made it optional.
We put blog posts out about this a while back
If you are using our Royal Mail direct integration to ship your Amazon orders we would recommend you have this switched on now but there is the chance your VTR may suffer
Amazon VTR - Royal Mail labels say "No Valid Tracking Number" on VTR Report
Amazons recommendation however is to buy shipping via them as they will be automatically classed as valid tracking
If you want to set this up and are struggling then please contact our support team for help