Same for me. I tested a Windows 7 x64 system which has all security patches, but caf's "really simple test" above still runs, which seems to indicate that the bug still exists. Same as you, I applied KB4088881, which was the only pending update, but it made no difference.

Also, I tried the command from the orginal article:

pcileech.exe dump -out memorydump.raw -device totalmeltdown -v -force

This creates 5GB file which does look like a raw memory dump. I'm not sure how to interpret this; I don't know what the behavior should be with or without the bug.