I thought of this but I've come to the conclusion it's probably nothing to do with the slot and just a problem with the unit's f/w when it boots. Because if I look in the slot with a flashlight the contacts look clean and shiny. I was thinking maybe it's the physical card detection switch (as SD card uses this to detect the card--signal CD). But then this makes no sense either because if I try to move/wiggle the card in the slot without pushing it in, it does nothing. I mean the card doesn't really move much if you try that but still should be enough to get an intermittent switch.

Also I can turn the unit OFF, wait for it to completely shut down and turn it ON again, and sometimes that's also enough for it to read the card--it's very random. This is with the vehicle completely stationary as well so nothing is moving around. I never lose the card while driving once it has been re-inserted after the unit has started either (something that would indicate a bad or dirty slot).

I've come to the conclusion it is not the slot at all; I can give the contact cleaner a shot (pardon the pun) but I doubt it will do anything. Right now I'm trying with everything but the ASR on the unit and the ASR on the card (I'm using 2015.10 for the moment until I find the ASR files for 2016.10). I've only booted it a few times but SD card has come up each time (going into developer menu and file manager and seeing the SD card is not greyed out); however that was only a few boots...have to try for about a week of normal use and check everyday if the SD card is recognized before I can be sure.