Dirty floor tiles not show up on load

janitors are cleaning the floor constantly but are not cleaning the dirt. even if they walk on it

====================
COLLECTED HARDWARE DATA
====================

Device
=====

Model: MacBookPro9,2

Operating system: Mac OS X 10.11.6

RAM size: 8 GB

Battery status: Charging
Battery level: 0,82

Processor Device
============

Type: Intel(R) Core(TM) i5-3210M CPU @ 2.50GHz
Core count: 4
Frequency: 2 GHz

Grahpics Device
===========

Vendor: Apple
Type: Intel HD Graphics 4000
Memory Size: 1 GB

Screen Summary
===========

Full Screen: True
Resolution: 1280 x 800 @ 60Hz