Microsoft Word ignores WebDAV LOCK timeout value since version 2509 (2024)

We're experiencing an issue where Microsoft Word (version 2509+) is ignoring the server-specified timeout value in WebDAV LOCK responses.

EXPECTED BEHAVIOR (per RFC 4918):
Our WebDAV server returns a LOCK response with a 5-minute timeout. Word should send LOCK refresh requests before this timeout expires to maintain the lock.

ACTUAL BEHAVIOR (Word 2509+):
Word is using its own internal timing (approximately 43 minutes) regardless of the server-specified timeout. Sessions expire on the server after 5 minutes without refresh, causing data loss and "session expired" errors for users.

EVIDENCE:
- Server LOCK response includes: Second-300 (5 minutes)
- Server logs show no LOCK refresh requests from Word until approximately 43 minutes after initial lock
- Previous Word versions (pre-2509) correctly respected the server timeout
- Issue affects multiple customers who upgraded to Word 2509+

IMPACT:
Users lose work when editing documents in Word via WebDAV because sessions expire without Word refreshing the lock.

QUESTIONS:
1. Is this an intentional change in Word's WebDAV client behavior?
2. If so, where is this documented?
3. Is there a registry setting or policy to restore the previous behavior?

REPRO STEPS:
1. Set up a WebDAV server that returns Second-300 in LOCK responses
2. Open a document in Word 2509+ via WebDAV
3. Monitor server logs for LOCK refresh requests
4. Observe that Word does not send LOCK refresh until approximately 43 minutes (far exceeding the 300s timeout)

Thank you for any guidance.