I don't know if this is your problem or not, but make sure you installed the "main" addon:
http://www.esoui.com/downloads/info65-InventoryGridView.html
There are several other addons posted that say things like:
Inventory Grid View Skin: Slide
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* The keyword is "Skin"
That means it modifies Inventory Grid View to make it look a little different. But you must still have the "main" Inventory Grid View Addon installed & running.
If that is not your problem look in the settings menu and see if there is an option to turn Grid View ON/OFF and make sure its turned on. I don't use it so I don't know if it actually has a setting to turn Grid View off, but its worth a look.