audio plugins not loading

Title: Audio Plug-In Manager scan hangs and returns no plugins (VST3 + AU) — 27.0.0.17 and 26.0 beta, macOS 26.5.2. Release Premiere scans the same folders correctly.

Environment: Premiere Pro (Beta) 27.0.0.17 and the prior 26.0 beta build. macOS 26.5.2 (25F84), Mac17,6, Apple Silicon, 64 GB. Audition (Beta) exhibits the same. Premiere Pro 2026 release and Audition release on the same machine are unaffected.

Symptom: Preferences > Audio > Audio Plug-In Manager, folder list contains only /Library/Audio/Plug-Ins/VST3 (VST2 paths removed). Click Scan for Plug-Ins with Rescan existing plug-ins checked. Beach ball, then the Available Plug-Ins list is empty — no VST3, no AU. Effects > Audio Effects shows only Adobe built-ins. ~/Library/Preferences/Adobe/DVAAudioFilterScan is never created after the scan.

Control: On the same machine, Premiere Pro 2026 release launched after DVAAudioFilterScan was deleted, rebuilt it on its own, and loads every third-party plugin (iZotope Ozone/Neutron/RX/Insight, UAD, Brainworx, Soundtoys, Plugin Alliance). Release Audition also loads them. The beta cannot, on either build.

Steps already taken, no change in the beta:

• Full prefs reset via Option launch, with Reset Plugin Loading Cache checked
• Deleted ~/Library/Application Support/Adobe/Premiere Pro (Beta), ~/Library/Caches/Adobe/Premiere Pro (Beta), ~/Library/Preferences/Adobe/Premiere Pro (Beta), ~/Library/Preferences/Adobe/Audition (Beta), ~/Library/Preferences/Adobe/DVAAudioFilterScan
• Verified all in-scope VST3 and AU binaries are arm64 or universal via file
• Removed com.apple.quarantine recursively from /Library/Audio/Plug-Ins/VST3 and /Components
• Moved every Intel-only and known-problematic plugin (legacy Native Instruments set, iZotope DDLY, Predator) out of the plugin folders before scanning
• Rebuilt AU registry (killall AudioComponentRegistrar)
• Rolled back to the prior 26.0 beta build; that build had shown plugins previously (cached scan). A forced rescan on 26.0 now returns empty as well.

Diagnostics:

• Crash report from 2026-08-14 17:03 (27.0.0.17), attached: SIGABRT, abort() called, faulting thread 0. Every frame in the crashed thread is inside the Adobe Premiere Pro (Beta) binary — no third-party plugin bundle, no CoreAudio/AudioUnit framework in the stack. Repeating frame offsets suggest a loop or recursive dispatch immediately before abort.
• Plugin Loading.log from the beta profile (attached) shows only MediaCore effects-loader scanning (file types *.bundle, *.plugin, *.prmp, *.vst across app PlugIns and Adobe/Common/Plug-ins/7.0/MediaCore). No entries for /Library/Audio/Plug-Ins/VST3 or /Components after a forced audio scan.
• Unified system log (log show --last 2h) filtered for Premiere/audio/vst/scan/filter/component during and after the forced beta scan contains only CoreAudio device I/O from the release Premiere Pro 2026 process. Zero entries from Premiere Pro (Beta) related to plugin scanning.

Read: the audio plug-in scanner in the beta stream is not completing (or not spawning) on macOS 26.5.2, independent of build number and of what plugins are on disk. Release builds on the same machine scan the same folders successfully.

Impact: Projects saved in 27.0.0.x cannot be opened in the release build, so there is no way to mix a v27 project with third-party audio effects. Working around it via AAF to Audition release.