Lost MX records, unable to create new ones

I use Gmail for my email handling, and I had previously set up three domains registered on dynv6 with MX records pointing to Gmail. As of now, all the MX records are gone for all three domains.

When I try to put the MX records back, I get an error that the Data field “must be a valid hostname” and am unable to Save the form.

Values I’m using when attempting to create the new record:

Type: MX
Name: (blank)
Data: ASPMX.L.GOOGLE.COM (also tried with a period at the end of the name, same error)
Priority: 1

Have I made a mistake somewhere, or is this a known issue being tracked somewhere else? Thanks for any advice!

Found the answer – the hostname needs to be in all lowercase (so “aspmx.l.google.com.” works). I’m leaving the post up in case this answer helps someone else, or in case it’s useful for people to have another data point of lost MX records.