I have created an AWS lambda that works well when I test it and when I create a cron job manually through a cloudwatch rule.
It reports metrics as invocations (not faile
If you are looking for the reason your invocations are failing, see the other answers UNLESS you're trying to implement AWS::Events::Rule and you're seeing failed invocations. The following answer may resolve the issue and negate to need to find these non-existent logs.
Cloudwatch failedinvocation error no logs available