Unfortunately unsuitable for performance 10-30 Watt

I have chosen this transformer, since I wanted to replace my old halogen spotlights with LEDs in the bathroom. The halogen spotlights (6 pieces) each had 35 watts of power. According to a new wiring I have interconnected all 6 spotlight and wanted to buy a transformer that can handle the now lower wattage. The old transformers have 50 to 150 watts of power and were therefore unsuitable.
The 6 LED spotlights à 5 W have a total of 30 watts logically. So I opted for this transformer, as the manufacturer promises a window of 10 to 60 watts.

When I connected the 6 LEDs on the transformer, I could already see a slight flickering. However, after about 5 minutes this slight flickering changed into a "disco" mode. The LEDs went on and off like in a disco.

I had originally planned yet, new to wire another room where 5 LEDs should be placed. However, I must seek this by another transformer, as this causes problems already at 30 Watt. At 25 watts I see black.

Therefore, my conclusion is bad.
The transformer is not suitable for clear performance decreases below 30 watts. How that looks at higher wattages between 30 and 60 watts, I have not tested.