2018 Subaru Outback 2.5L Engine Oil Change with EWK 6.5L Extractor Failure - What could be wrong?

I thought I'd try one of those pump oil extractors for my next oil change on my wife's 2018 Subaru Outback 2.5L. I bought the EWK 6.5L unit off Amazon and gave it a shot.

After about 45 minutes of pumping it, I got about 1.5L of oil out of this engine that holds 5.1L. I did measure the oil level before starting and it was full.

What am I doing wrong? If you've used this type of extractor before or if you have this same year model vehicle and know why an extractor won't work or what you have to do to get one to work, please let me know in the comments.

Thanks for watching!