"@" A-Record not validating with website host

When creating an A-Record with "@" our website hosting server is unable to validate this. The www A-record validated almost immediately.

When looking at DNS checks for the domain, we receive an error (but without any error direction), but if we look up specifically "@.example.com" it comes back successful. I am wondering if the period after the @ is causing a problem. AWS adds that period automatically and I cannot remove it. The website host says it must be on AWS side.

Any ideas would be helpful. Thank you in advance.