SQL Server 64-bit - Import from Excel
Just as a work around (since you said running the package manually works): you should be able to run the dtsx package using T-SQL via a job or make a stored proc to be called by a job, as this article explains.

For a package in the server:

DECLARE @SQLQuery AS VARCHAR(2000)

DECLARE @ServerName VARCHAR(200) = 'ARSHAD-LAPPY' 

SET @SQLQuery = 'DTExec /SQL ^"\DataTransfer^" '
SET @SQLQuery = @SQLQuery + ' /SET \Package.Variables[ServerName].Value;^"'+ @ServerName + '^"'

EXEC master..xp_cmdshell @SQLQuery
GO


For a package in the file system:

DECLARE @SQLQuery AS VARCHAR(2000)

DECLARE @ServerName VARCHAR(200) = 'ARSHAD-LAPPY' 

SET @SQLQuery = 'DTExec /FILE ^"E:\DataTransfer.dtsx^" '
SET @SQLQuery = @SQLQuery + ' /SET \Package.Variables[ServerName].Value;^"'+ @ServerName + '^"'

EXEC master..xp_cmdshell @SQLQuery
GO