I can sudo. Last time I looked into this, Memtest86+ version 6 was required to work with UEFI but it wasn’t available for Ubuntu 22.04. Now it seems that 24.04 has it, so I might update and see if I can get the test running. Thanks for the suggestion!
It’s not hard to reproduce, but it’s annoying that when they finally came here to check it, no problems happened. I had to bug them so much to even get them to have a look.