The Knock spell does not open magical locks other than Arcane Lock
The first part of the description of the spell specifies that you choose an object. It makes absolutely no statement about the object you choose being guaranteed to be unlocked by the Knock spell.
It then specifies conditions for if your target is a mundane lock.
Finally, it specifies conditions for the object is held shut with Arcane Lock.
If neither of those applies, the spell is silent with regards to opening the lock.
When choosing an object, you don’t need to know what bars it shut
The fact that the spell mentions a “magical means that prevents access” doesn’t imply that it can open all magical locks. It just means that your character can look at it and say “Hey, this object is locked/barred/stuck! I might be able to open it, and I can certainly select it as a valid target!”
Whether it works or not depends totally on the type of lock, with only mundane locks or things locked with Arcane Lock being affected by the spell.
(Although it appears any target will make a loud noise, as the spell doesn’t specify that it had to be successful to make the knock sound.)