Hi Usman, Mike, I am facing another issue similar to what you face when I try to depend on global variables to filter data on further screens.
Assume that you set value of a global variable on an event (e.g someone clicks a gallery item). And the global variable is used to filter out a gallery on the next screen. In many tests i did this usually works 50% of the time and other times you just see a blank gallery on the next page. Maybe powerapps has actually already evaluated the filter expression before the global variable is set. Are you aware how this issue could be dealt with. What is the best practice to use, Set or update context, what can be done to ensure reevaluate the filter expression when the global variable changes.
I don't know why you have this issue. Can you please provide the OnSelect formula "(e.g someone clicks a gallery item)" and the Items of Gallery on the second screen that you have the filtered result set?