You can turn on “Logging asdm informational” but ensure before any messages are sent to the ASDM log buffer, you must enable logging using the logging enable command.

When the ASDM log buffer is full, security appliance deletes the oldest message to make room in the buffer for new messages. To control the number of system log messages retained in the ASDM log buffer, use the logging asdm-buffer-size command.

The ASDM log buffer is a different buffer than the log buffer enabled by the logging buffered command.