Flickering LED on BP3106 based LED Driver
According to the specs and the lamp data you provided, you may be experiencing a UV protection in your circuit. The spec say that the output voltage should lay between 75V and 100V and you wrote you are connecting 5x12V LEDs in series. Therefore, you have a total of about 60V load into the driver. Most probably the circuit starts, detects the under voltage, turns off and tries to re-start again. This may be the reason for your 2Hz flicker. Try adding more LEDs in series to reach the minimum required load voltage (75V).
PS. Could you provide a link to the datasheet in English?