Premiere Pro 25.x: HEVC 8K Decoding Fallback to CPU– Works in 24.x but Stalls in 25.x

After a clean Windows 11 install, all Premiere Pro 25.x versions (25.0, 25.1, 25.5 – tested extensively) exhibit a severe regression when working with 7680×7680 HEVC (H.265) MP4 files:

• Initial ~60 seconds: full NVDEC hardware decoding on my RTX 3080 Laptop GPU (Video Decode 50–80 % in Task Manager)
• After ~1 minute: silently falls back to CPU/software decoding → Video Decode drops to 0 %, CPU spikes to 100 %, rendering stalls at minutes-per-frame
• Issue occurs even with simple edits (only new audio added, no video effects) when exporting to ProRes 422 HQ or H.264/H.265
• Identical clips, identical project, identical drivers, identical hybrid GPU BIOS setting → 100 % smooth real-time playback and fast exports in Premiere Pro 24.x (24.6 tested)
• In 25.x the same project immediately triggers the fallback and becomes unusable

System Details:

• Windows 11 24H2 (clean install)
• Intel Core i7-11800H + NVIDIA GeForce RTX 3080 Laptop GPU (16 GB)
• Latest NVIDIA Studio Driver (clean install)
• Intel UHD Graphics drivers up-to-date, BIOS set to Hybrid
• 64 GB RAM, media on NVMe SSD
• GPU Sniffer confirms full CUDA detection, 16 GB VRAM, no restrictions
• Renderer locked to CUDA (OpenCL also available in hybrid mode)

Reproduction Steps:

1. Import any 7680×7680 HEVC MP4
2. Create sequence matching source
3. Add new audio track (no video edits)
4. Export or render timeline → stalls after ~1 minute in every 25.x release
5. Open identical project in 24.x → exports in real-time

Proof that it is a 25.x regression:

• Downgraded to Premiere Pro 24.6 → issue completely disappears
• Upgraded back to 25.0 / 25.1 / 25.5 → issue instantly returns
• No amount of cache clearing, driver reinstalls, or hardware decoding toggles fixes it in any 25.x version

This is clearly a regression introduced with the 25.x branch (most likely tied to the decoder priority changes or stricter NVDEC limits added in 25.x) and still unfixed in the latest stable release (25.5).

Please escalate this to the engineering team.