I only want a pipeline step like a filter-boost to execute when a variable is not being sent in the query. I have a condition like the following condition: !myVariable on the step, but it doesn’t work as expected and when saving the pipeline its removed.

The Solution:

Due to ! being a special character we need to wrap the condition in quotes to force it to be interpreted as a string i.e. condition: "!myVariable"

Your condition should now save and work as expected.