Premiere Pro 26.5.2 (Windows) freezes for minutes - "Not Responding" + "Media Pending" when an accessibility / UI Automation tool reads the window

Premiere Pro version: 26.5.2 (Build 5), latest release
OS: Windows 11 Pro 26H2, build 26300.9818 (also reproduced on 26300.9711)
Hardware: Intel Core i9-14900KS, 64 GB RAM, NVIDIA GeForce RTX 5070 Ti 16 GB (Studio driver 621.14) + Intel UHD 770 (driver 32.0.101.7092)
Media: 4K 3840x2160 HEVC 8-bit Rec.709, ~60 fps, ~65 Mbps
Project: one 4K/60 sequence, 4 minutes, 100 caption segments, transcript, 6 B-roll clips, 7 PNG graphics, 7 Lumetri instances, 1 music track
Frequency: 100% - every time a UI Automation client queries the Premiere window after this project is loaded

SUMMARY
Premiere Pro 26.5.2 becomes "Not Responding" for minutes (more than 2 minutes measured; sometimes it never recovers) whenever an external UI Automation / MSAA (accessibility) client requests the Premiere window's accessibility tree. During this time the Program Monitor stays on "Media Pending" and the timeline is unusable. Windows Reliability Monitor logs AppHangB1 (consent key AppHangXProcB1).
With no UI Automation client attached, the SAME project on the SAME machine opens in 2-10 seconds and plays, scrubs, saves and reopens normally. GPU, drivers, media, plug-ins and project data were all ruled out.
This matches the "Acknowledged" accessibility / Magnifier freeze threads for 26.2-26.5.x. This report adds the exact code path.

STEPS TO REPRODUCE
1. Windows 11, Premiere Pro 26.5.2. Open a project with a populated timeline (captions, several clips, effects).
2. Run any UI Automation client that reads the Premiere window's accessibility tree (reported triggers: Windows Magnifier, Text Cursor Indicator, Power Automate; in my case an AI computer-use agent that reads window text/tree through UI Automation).
3. Let the client query the Premiere main window.
Expected: Premiere answers quickly (or off the UI thread) and stays responsive.
Actual: Premiere's main UI thread runs at 100% of one CPU core inside its own accessibility code for minutes. The window becomes "Not Responding" and the Program Monitor shows "Media Pending" until the call finishes.

EVIDENCE - UI THREAD STACK DURING THE HANG
24 of 24 identical samples over 40 seconds (live stack walks of the UI thread). Thread state: Running, not waiting.
  Adobe Premiere Pro.exe - deep recursion, same frame repeated (100% CPU here)
  ... Adobe Premiere Pro.exe!pion::algorithm::xml_encode+0x93160a (x6, recursive)
  ... Adobe Premiere Pro.exe!pion::algorithm::xml_encode+0x931732 / +0xa0bbd5 / +0xa4bce9 / +0x955de8
  ... Adobe Premiere Pro.exe+0x185ee280 / +0x18692585
  ... Adobe Premiere Pro.exe!pion::algorithm::xml_encode+0x954eba (window procedure)
  USER32!CallWindowProcW
  USER32!SendMessageTimeoutW  (WM_GETOBJECT)
  OLEACC!AccessibleObjectFromWindowTimeout
  UIAutomationCore (servicing an incoming UI Automation request)
  USER32!PeekMessageW  (Premiere main message loop)
  Adobe Premiere Pro.exe!HandlerTools::CreateModule+0x482d2
(Symbols are the nearest public exports because no PDBs were available. Adobe can resolve the offsets against build 26.5.2.5 symbols. A minidump captured during the hang is available for Adobe engineers on request.)

EVIDENCE - CONTROLLED A/B TEST (same project, same machine, one variable)
With UI Automation client attached:
 - UIAutomationCore.dll loaded in Premiere: YES
 - Project open: never completed (UI thread 99-100% for more than 2 minutes)
 - Windows "Not Responding": YES
 - Program Monitor: stuck on "Media Pending"
 - Playback / scrub / save / reopen: impossible
Without any UI Automation client:
 - UIAutomationCore.dll loaded in Premiere: NO
 - Project open: 2-10 seconds
 - Windows "Not Responding": never
 - Program Monitor: frame shown immediately
 - Playback / scrub / save / reopen: all normal

ALREADY RULED OUT
- No GPU TDRs, LiveKernel reports, BSODs or WHEA errors
- Latest NVIDIA Studio and Intel drivers; HEVC decodes in real time (Intel Quick Sync), rendering on CUDA
- No third-party plug-ins; Plugin Loading.log is clean
- Preferences reset; media cache checked
- Project data is valid: Premiere opens, saves and reopens it normally when no UI Automation client is attached
- Turning off hardware decoding and GPU UI rendering made no difference (expected: the hang is CPU-bound in accessibility code)

IMPACT
I am a professional content creator on a paid Creative Cloud subscription. This bug has blocked my editing for days, with repeated "Not Responding" hangs, lost time and forced closes. It also makes Premiere unusable alongside Windows accessibility features and any modern AI or automation tool that reads the UI through Windows' standard accessibility API.

REQUESTS TO ADOBE
1. Fix this in a 26.5.x patch, not only in v27. The accessibility (WM_GETOBJECT / IAccessible) handler must not walk the whole UI tree synchronously on the main thread (build it lazily, cap the work, or answer off the UI thread).
2. Until then, add a preference to turn off Premiere's accessibility provider as a workaround.
3. Please confirm the internal bug ID and the target fix version.

I can provide the minidump and full capture files to Adobe staff privately.