M4 Pro MBP: Lightroom & Premiere leaving GPU idle during heavy exports (CPU bottleneck / 0 RPM fans)

Setup: M4 Pro (24 GB) | macOS Tahoe 26.6.2 | Lightroom Classic & Premiere Pro | High Power Mode

The Issue Tasks like AEB HDR merges, timelapse exports, and Premiere renders are running extremely slow. Under heavy workloads, the system never ramps up—fans stay completely silent.

Live Diagnostic (powermetrics during timelapse export)

• CPU: 100% load across 14 cores (~29–35W)

• GPU: Effectively idle at ~50 mW (0.05W)

• Thermals: Fans at 0 RPM because overall system package draw never trips thermal limits.

Lightroom/Premiere are failing to offload rendering to the GPU, leaving the CPU to bottleneck the entire export.

Troubleshooting Already Done

• Settings: Toggled GPU acceleration (Auto / Custom / Off) in LrC; set macOS to High Power Mode.

• Caches & Storage: Purged all preview, scratch, and media caches. Operating 100% on internal SSD (Disk Utility clean).

• Installs: Clean reinstalled Adobe CC and performed a clean macOS reinstall; tested in Safe Mode.

• Hardware: Apple Diagnostics passed clean; tested on OEM MagSafe and high-wattage USB-C PD.

Question: Has anyone found a workaround or config fix for Adobe apps failing to engage Metal/GPU acceleration on macOS Tahoe?