Oil is leaking around the HPU high-pressure filter area after changing the element.
Could be the O-ring needs to be replaced also. If the O-ring was replaced check to see if the retaining ring was also installed. The white hard plastic backing ring (AKA RETAINER-PACKING, BACK-UP FILTER BOWL) holds the O-ring in place while the filter element is being installed.
Without this, you could damage or distort the O-ring ruining the seal while installing the filter element. If this is missing or if the O-ring is missing it could explain leaking.
The retainer goes on the low-pressure side. The O-ring will face the high pressure.