Purge's forcelinkupdate option appears in several contexts to have become non-functional (as installed on ENWIKI), *probably* more than one and less than three weeks ago.
The earliest entries in https://en.wikipedia.org/wiki/Category:AfC_pending_submissions_by_age/0_days_ago will usually demonstrate the problem. Note that by reading the page, the articles appear categorized as much older than "0 days ago." A null edit will (as expected) correct this, a purge by itself (as expected) will not correct this. Until recently, purge with the forcelinkupdate option did (as expected) correct this, now it does not.
I believe I have observed similar changes in the behavior of my PERL-based bot, the Pywikibot touch.py bot, and the direct URL API.
Background: Multiple tools make use of the forcelinkupdate option on ENWIKI to update pages, including but not limited to Pywikibot and Joe's Null Bot. Generally these tools are used to deal with the fact that category inclusion for an article is not constantly reevaluated, so, a template, say, conditionally includes a category if the time has passed a certain timestamp will not be included in the appropriate category until or unless a full null edit or a purge/forcelinkupdate is performed. The latter is strongly preferred for many use cases to avoid polluting the article history.
See also: https://en.wikipedia.org/wiki/User_talk:Joe_Decker#CAT:AFC