There are two ways transactions are started in AXA. The first is manually by invoking the startApplicationTransaction and stopApplicationTransaction api methods (more information here:
https://docops.ca.com/ca-app-experience-analytics-digital-experience-insights-from-ca/ga/en/using/using-apis). When using the API, be aware that nesting startApplicationTransaction calls can lead to incomplete transactions. For example, if a transaction t1 starts transaction t2, ending transaction t1 does not complete t2. This transaction must also make a stopApplicationTransaction call to be complete.
In addition to transaction started from the API, AXA also automatically tracks transactions. This behavior is defined in the app profile under "Manage Apps" --> <App> --> Edit Profile. For example:
Mobile transactions
Un-checking "Automated" and saving the profile disables automatic transactions if these are not wanted.