If there’s air (such as bubbles or foam) mixed with the ingredients you want to process in your Philips vacuum blender, the vacuum process will not start. Your blender is designed this way to prevent air from being sucked into the vacuum system and being damaged.
Please note: foam usually appears as a result of blending right before starting the vacuum process.
To solve this problem, please wait until the foam has dissolved and then restart your blender (turn the knob to OFF position and then to ON position again).
To prevent this from happening: please avoid blending before vacuuming. But if you do, then wait until air/foam has dissolved before starting the vacuum process.