It is not recommended to add assertions manually to a VSM.
For example, "If learning" assertion has below XML when it created automatically.
----
<CheckResult assertTrue="true" name="If learning" type="com.itko.lisa.vse.stateful.AssertOnExecutionMode">
<log>Current execution mode is Learning, branching to Virtual HTTPS Live Invocation {{LIVE_INVOCATION_PORT}}</log>
<then>Virtual HTTPS Live Invocation {{LIVE_INVOCATION_PORT}}</then>
<executionMode>LEARNING</executionMode>
</CheckResult>
-------
If an assertion is added manually, then it will be like below:
<CheckResult assertTrue="true" name="If learning" type="com.itko.lisa.vse.stateful.AssertOnExecutionMode">
<log></log>
<then>Virtual HTTPS Live Invocation {{LIVE_INVOCATION_PORT}}</then>
<executionMode>VALIDATION</executionMode>
</CheckResult>
The above information is not correct, which will cause the issues in "Learning mode".
It is recommended to create a new Virtual Service, which will add all the default assertions automatically.