For the "Tracking uploaded on time and validated" metric alone, your rating will never go below Above Standard, as long as you or Pirateship make sure that the sales in question have been "Marked As Shipped" in your Seller Hub. It can drop you out of TRS to Above Standard, but not lower than that by itself.
I sell a lot that uses USPS First Class Letter or First Class Envelope, where the USPS does not even issue tracking numbers. EBay makes allowances for this in service metrics, as long as a seller makes sure that those items are marked as shipped in their Seller Hub > Orders. I use Stamps.com for all of my shipping, and it automatically marks my FC Large Envelope sales as shipped for me at eBay, without a tracking number. For those FC Letter items I send with a stamp or two, I manually mark them as shipped in my Orders tab. That is the only metric that has me below TRS, at 66%, but a seller will not drop below Above Average just on "Tracking uploaded on time and validated".
SO unless TRS status is important to you (it never materially helped my sales when I had it), it is nothing to worry about on its own if you make sure the affected sales are marked as shipped... UNLESS a scamming buyer wants to claim that they never received the item, at which time you'll have to refund them. That is the only caveat, and with a couple thousand USPS First Class sales, only a handful over the years had to be refunded.
If you're still concerned about no tracking number being allowed to be uploaded, do NOT telephone what appears to be eBay Customer Service. It's an outsourced joke and is actually Customer No-Service where they will lie or tell you anything just to get you off the phone. Instead, contact an actual eBay employee at eBay For Business on Facebook and use the message button in the upper right to get things started. The actual eBay employees on the other end have been quite helpful in the past for a lot of us sellers.
Cheers, Duffy
