I have installed the latest Elementary OS Loki Release (not a BETA version). Sometimes when the system wakes up from sleep, after I log in, I see this behavior of the system. Almost all the text is gone as you can see in the picture: The Application Menu, System Settings, Notifications bubbles, Terminal, Files, (all apps). The problem is solved when I reboot the OS.
P.S. I mention that I installed elementary tweaks from this github project, but I don't think that it has to do with this bug.
So how can I solve this problem? Is it a known bug that will be solved in some future updates? Can it be a graphics driver issue?