In my apigee cloud account, I misspelled the word Condition as Conditon.
<Name>RF-Missing-Something</Name>
<Conditon>(isNull is true)</Conditon>
The proxy was saved and deployed successfully without any error. Traffic was also allowed but the Condition was not matching and hence Raise Fault was executed for all calls.
I know this is my fault as I misspelled the word. But I spent about 15mins to rectify my mistake.
I tried the same on my On-prem 4.18.05, when I misspelled, the proxy doesnt even save and an error is thrown, which is great and saves time 
