When a condition is not met, Katalon Studio returns a result (either True or False) with a warning message regardless of what failure handling settings you specified.
In other words, Katalon Studio continues running despite a test's failure. This behavior is similar to choosing the Optional value for failure handling. See: Failure Handling.
In case the waiting keyword fails due to such errors as a network problem, session timeout, or because the AUT didn't start, failure handling then applies your specified settings.
For example, if you use the waiting keyword,
WaitForElementPresent, Katalon Studio only returns a True or False result in respect of the element's presence. If the element is not present on the current view, Katalon Studio returns a False result and shows a warning message (Failure Handling = Optional).
If you want to let the test case fail due to the element not being present, use the following script to make it an assertion:
boolean present = Mobile.waitForElementPresent(findTestObject('...'), 10)