Change of address/sitemap indexing - google search console

[ALPHAᵍᵐ]

Hi I just bought a new domain and now using it as my primary domain, old domain redirects to new one

I am trying to submit my new sitemap for indexing but It keeps saying "Couldn't fetch"

I also tried changing of address from the old property to the new property but still not working.

Your help will be highly appreciated thank you.

Old domain: enhle.co.za

New domain: enhlebeauty.co.za