SRAM eTap AXS HDR brake fluid not flowing – lever issue?

Hi, my brake fluid is not flowing through the system. I performed a complete disassembly and found out the issue must be between brake lever and the reservoir – based on the fluid can flow through other parts when I connect them separately. What might be wrong and how do I fix it?

BTW on the video there is an negative pressure in the top syringe and I apply a pressure to bottom syringe.