Thinkpad X13 Gen5 2-in-1 USB-C Charging Issue

Hello (special greetings to thinkpad nerds)

So, I recently bought a used Lenovo X13 Gen 5 2-in-1 (21LX) and everything has been great so far, passing all tests and a pleasure to use.

After the laptop slept while charging my phone via USB-C, both ports stopped charging and providing power/data. Lenovo Vantage reports “No power adapter plugged in.” The LED between ports flashes amber briefly on boot, then goes off. Device Manager previously showed Code 43 (UCSI PPM timeout) and uninstalling USB/UCSI/Thunderbolt drivers removed the error but ports remain inactive. I tried both ports with original 45 W adapter as well as a 67W charger I've used before with it without problems.

BIOS does not detect AC. I tried full EC/power reset (40s power hold, 2 min unplug) and shift+shutdown: charging LED flashes but does not stay on. The USB-C ports are the only ones for charging. OS is Windows 11 25H2.

It's becoming my main (and only) laptop for university and hopefully writing my thesis later this year. I've opened a ticket with Lenovo support since the warranty is still good for another 2+ years and I'm waiting. Any help is appreciated.