Hm... didn't realize this program came from here.
So... in windows 10, problem is, when the PC has been on for a while the details pane randomly disappears from the initial explorer instance. I can get it to appear again by creating a new explorer instance - either explicitly launching windows in a new instance or just restarting the initial one(though sometimes that has other undesirable side effects). But hey, that's advanced power-usery stuff and who has time for that. Would appreciate a fix.