@Shiny Xu,
It appears that you have a graphics compatibility issue. Have you tried switching your graphics to compatibility mode? As shown in the screenshot below, check the Compatibility Mode box, then restart FlexSim:
If this fixes the problem, then you have confirmed a graphics incompatibility is the problem.
In this case, please explore the suggestions outlined in this linked graphics article. You will want to start with updating your graphics driver. The latest driver for your Quadro K600 is here, and is up to version 411.95, released Nov 15, 2018. It appears that your current driver version is 358.91 from Nov 10, 2015.
I suspect that upgrading to this latest driver, and configuring the Quadro-specific settings discussed in this linked graphics article will solve your problem.
Be sure to disable Compatibility Mode in testing various solutions. From the article:
Compatibility mode/Generic Context is not intended for long term use.
Revert to this mode only if you must use a computer that doesn't meet
FlexSim's system requirements.
Please let us know how it goes.