My daughter had this problem. I tried to upgrade firmware and split cables, but it would not work on blu-ray, only DVD.
I connected the SE-506CB to my windows 10 desktop which had an old version of Cyberlink PowerDVD installed. This program tried to start the blu-ray film, but crashed.
I then upgraded Cyberlink PowerDVD to a newer version and SE-506CB worked as it should with no problems.
Your SE-506CB will work on DVD, but not on Blu-Ray because of DRM copy protection and because DRM will come in newer versions and your software (like PowerDVD which also plays blu-ray) have to be updated.
PowerDVD is not free, but maybe there is a demo version?
I hope this will help.