Battlecruisers, manoeuvre, and magazine-loss myths

Why did British battlecruisers suffer magazine explosions?

They were often used in battle-line conditions that constrained their designed advantage of high-speed manoeuvre.

British battlecruisers were never designed to suffer habitual magazine explosions. Several were lost that way while fighting in conditions that did not suit their survival concept. High-speed manoeuvre to port or starboard was meant to complicate enemy fire. A rigid battle line removed that freedom, turning an operational employment problem into an apparent indictment of the entire ship type.