This item is A CD which I posted as a large letter, which did not give me the option of getting a tracking number. The problem persists.

Well, there are options to buy pre-paid large letter envelopes with tracking.

 

Besides the point, you didn't answer my question.

 

How can I help you if you don't help me?

I use a personal computer. I stress that I have marked items as sent both before and after this CD.

Whoop, OK I guess i'm speaking to the same person 🤣

 

If you tuned up your PC and it's still happening, try getting in contact with live chat.

 

Have you got a iphone with an ebay app? you could try marking it as sent on there.