Yep. Same here. I have a Windows 7 system (64 bit Windows Pro) and iTunes 12.4.0.119. I can edit the "Release date" field but iTunes doesn't save it.
I seriously wonder if they actually do any regression testing before releasing new versions. It seems that they're only concerned about getting it out but don't give a second thought to making sure they didn't break any functionality! In a former lifetime I was a software engineer and I would get my *** chewed out by my boss if I ever let something like this slip through to the testing group! We did our own regression testing and only once we felt that we didn't hurt any existing functionality would we then give it to the QA group.
Anyone else here remember when iTunes 12 first was released back around Oct 2014? Not only did it show the "Release date" as "6/5/1905" but it actually changed the "Release date" field in all of the TV shows in my library. That was flat out data corruption (and I never heard Apple ever apologize for this).
This time it's looking like they just don't save the field.
It's odd how a company with such a great reputation in so many areas can fail so spectacularly so often.
Anyone taking bets on how long it'll take them to fix this? I'm guessing by July 4th, 2016. Yea, I know it's a bit optimistic and it'll like take them well into the fall but I'm hoping for a quick fix. They hardly ever get bugs fixed quickly so maybe they'll finally realize that people like it when products continue to work properly!
Larry.