With FSM 5.6 the database.xml structure was slightly changed and FSM 5.6 is supporting only the new database.xml structure.
This is leading after upgrade to a loss of the configured symbols (only the symbols, not the content of the devices configured on the floor plans).
Therefore after upgrading from older FSM version (e.g. 5.2) to 5.6, the already configured symbols of sensors on maps are not shown correctly, they are shown are dots/circles.
Please note : If before executing the file provided below the application was opened and the sensor properties were edited by approving > at that step the symbols changed to the default symbol and the previously configured symbol cannot be recovered.