Hi MarleneM,
Thanks for contributing to our forum. Our system is set up such that the Dimensions fields are only activated when using a shipping service and package size combinations for which they are necessary, and I see that our site is not currently allowing package dimensions to be entered when Parcel Select is selected as the only shipping service.
I just completed some testing with respect to this potential issue and noticed something very strange about how this is handled on the eBay Sell your Item and Revise your Item forms which makes it difficult to tell exactly how these circumstances should be handled, but I have forwarded the details to our technical team for further investigation.
Once I confirmed that I could not enter package dimensions when posting an item through Auctivw with Parcel Select as the only shipping service, I checked the eBay Revise your Item form for the listing and found that I was allowed to enter the dimensions there.
However, when I stepped through the process of completing a new listing using the Sell your Item form directly on the eBay site, I found that the Dimensions fields became hidden as soon as I selected “USPS Parcel Select” from the “Services” drop down menu.
I'll keep you posted on this issue as any new information becomes available. We apologize for any inconveniences this may have caused.
-Mike