CALayer with valid contents and correct configuration is excluded from window compositing on Apple Silicon (works fine on Intel)

macOS/Hardware details:

• macOS version: 27.0 (build 26A428)
• Hardware: Apple Silicon Mac (arm64)
• App architecture: Native arm64
• Xcode/SDK: Built against MacOSX27.0 SDK
• Deployment target: MACOSX_DEPLOYMENT_TARGET = 26.0
• Regression history: Same app/codebase previously built and ran correctly on macOS 13 (Ventura), Intel — issue only appears after migrating the build to Apple Silicon; no changes were made to the affected view's drawing or layer-configuration code between the two builds

We have a custom, layer-backed NSView (part of a hand-rolled tree/list control that draws its own content via Core Graphics into the layer's contents) that renders completely blank on screen on Apple Silicon Macs, while an adjacent sibling view using the identical view class, drawing code, and layer configuration renders correctly.

Using lldb and Xcode's View Debugger against the live process, we've confirmed:

• The layer's actual backing content is correct: capturing it directly via -renderInContext: produces the expected fully-drawn image (text and icons all present).
• Every inspectable property of the broken view/layer (hidden, alphaValue, opaque, wantsLayer, isFlipped/isGeometryFlipped, zPosition, masksToBounds, contentsScale, mask, transform, backgroundColor, contents, sublayers, superlayer) is identical to the working sibling view — no configuration difference exists anywhere.
• The layer's superlayer link is intact and points to the correct parent, ruling out a detached/orphaned layer.
• Standard remediation attempts — setNeedsDisplay:, displayIfNeeded, toggling wantsLayer, detaching/reattaching the view from its superview, changing zPosition — all have zero effect.
• Most notably, directly setting layer.backgroundColor to an opaque solid color on the live, correctly-connected layer (verified via property readback) produces no visible change on screen at all.

Because even an unconditional background color change is not reflected, the layer appears to be excluded from what's actually sent to the window server for compositing, rather than simply failing to draw updated content. Since all inspectable state is correct and identical to a working sibling view, we've been unable to identify any application-level cause. The view remains fully interactive — clicks and hit-testing resolve correctly to the right underlying data — only the visual output is missing.

Are there known Apple Silicon-specific changes to CALayer/NSView compositing (window server layer inclusion, contentsScale/backing-store allocation, or layer-backed view promotion) that could cause a fully valid, connected CALayer with correct contents to be silently dropped from the composited frame? Any suggestions for further diagnostic tools (e.g. Quartz Debug, CARenderServer logging, or WindowServer compositing traces) to narrow this down further would help.