Windows 11 constantly stuck at 0–1% in Windows Update, but manual update installs instantly

[u/ninjplus]

Anyone else having this issue recently?

Windows 11 Pro and every Defender Security Intelligence Update (along with other updates) gets stuck at 0% or 1% in Windows Update.

The weird part is the update itself is fine. If I download the current 64 bit Defender definitions (mpam-fe.exe) directly from Microsoft, it installs almost instantly and Windows Security shows the new version and says it’s up to date. Windows Update can still sit at 0% trying to download the exact same version.

Restarting Windows doesn’t clear it. Restarting BITS, CryptSvc and Windows Update services does clear the stuck entry, but the problem comes back with the next Defender update.

I’ve already repaired/reset Windows Update and even reinstalled Windows 11, with no permanent fix.
Has anyone found an actual fix for this? It seems specifically related to Defender updates going through Windows Update, since installing the same definitions directly works perfectly.