You're not alone. My headset updated to V81.0 and my PC app shows Meta Quest Link App Version 79.0.0.1143.381. The cable is recognized (I get the "allow USB files" message and hear the tones), but PC Link absolutely won't work. After many attempts to get wireless working, it connects, but the display shears, lags, stutters, and the hand controllers look like a drunk person is using them. Completely useless device now.
I was advised to enable PTC in the Meta Link app (Settings -> Beta Version -> Enable PTC). Then close the app. The app should update. After that, the versions in the Horizon OS and Meta Link app will match. After that, it worked for me immediately.
Thank you. Because several others had said that idea DIDN'T work for them, I was reluctant to try it. But...I did, and so far it's working.
