I recently sold my 2019 Macbook Pro on Ebay. I did a factory reset and shipped it off. Now the new owner is saying they can't transfer any files because the disk, "Macintosh HD-Data" is locked. I gave them the password I used for that computer and hopefully it will work out for them but I thought doing a factory reset would keep that from happening. Did I maybe miss a step?
Did you perform a clean install of macOS by first erasing the whole physical drive? After installing macOS and you are greeted by Setup Assistant, then you need to Shutdown the Mac (you may need to first select the language before you may be able to access the Apple menu to initiate shutdown). This will leave the Mac ready for a new user to setup as their own.
Personally, even if someone did this for a Mac I have purchased used I would still perform a clean install of the OS myself to ensure the drive has been erased and there is absolutely nothing on it from the previous owner. I don't trust other people to do things properly or not to include something nefarious on it.
FYI, here is an Apple article for the steps you should have taken before selling your Mac:
Did you perform a clean install of macOS by first erasing the whole physical drive? After installing macOS and you are greeted by Setup Assistant, then you need to Shutdown the Mac (you may need to first select the language before you may be able to access the Apple menu to initiate shutdown). This will leave the Mac ready for a new user to setup as their own.
Personally, even if someone did this for a Mac I have purchased used I would still perform a clean install of the OS myself to ensure the drive has been erased and there is absolutely nothing on it from the previous owner. I don't trust other people to do things properly or not to include something nefarious on it.
FYI, here is an Apple article for the steps you should have taken before selling your Mac:
Sold Macbook on ebay now new owner asking for HD-Data password
