-That is what expected behaviour generally from IMAQdx Get Image. -It waits untill the image is available or reaches timeout(default 5000ms). -If required you can reduce this timeout and handle appropriately with timeout error coming from IMAQdx Get Image to allow the execution.
-As mentioned earlier one way is to reduce timeout Or -Check Grab and Attributes Setup example to use Buffer Mode Or -Have Separate loop for UI and Image Acquisition(Producer(UI)-Consumer(Image Acquisition))