Shift key functionality stops after alt-tabbing

[detectivepikachu 0]

If I alt-tab out of WoW, when I alt-tab back in some functionality with shift key stops working.  Examples include shift-clicking a quest to track it or holding shift when hovering over an inventory gear to compare it to the currently equipped item.  Before alt tabbing those work, after alt tabbing I can't shift click quests and the compare window doesn't show up when I hold shift and mouse over an inventory gear.

I'm running WoW in windowed-fullscreen mode and I have no addons, overlays, macros, or keybindings.  I feel like I remember this issue from way back when I used to play WoW regularly (BC-WotLK time).  Any help tips or advice is appreciated.  Thanks!

[Starz 2]

Found the Blizzard post here for this issue: 

 

https://eu.battle.net/forums/en/wow/topic/5493989825