This has been present ever since the Scared emotion was added to the game.
When a Servo gets scared (which honestly feels strange anyway with them being robots) their protrait picture will display the Sad expression with the tear on the face and the actual Servo in the game will have no expression at all. As in, the face is blank.
I do use mods but have removed them to check.
I own EP01, EP02, EP03, EP04, EP05, EP06, EP07, EP09, EP10, EP11, EP12, EP13, EP17, EP18, GP01, GP02, GP03, GP04, GP05, GP06, GP07, GP08, GP10, GP12, SP01, SP02, SP03, SP04, SP05, SP06, SP07, SP08, SP09, SP10, SP11, SP12, SP13, SP14, SP15, SP16, SP17, SP18 and a handful of Kits.
Edit by Crinrict: Adjusted title to fit migrated bug report: [ARCHIVED] [DU] Scared Servos don't have appropriate facial expressions | EA Forums - 11449596
Archived thread had around 20 me toos
