What is the actual issue, that you are not getting data correctly? As you didn't describe how the gallery gets data or what it expects.
So its hard to tell you why a gallery doesn't show what you want, when I do not see pictures showing us when its wrong and an explanation of why the data you use is wrong.
What should the data say
What does the data say
What is Start
What is End
looking at your Expression
Should your second one be _firstDayInView?
I mean you have essentially the exact same code in BOTH places which means you shouldn't get squat as its going to create the exact same Date, shouldn't your End be out there further??? As everything after the && is exactly the same as before which means... you have zero milliseconds difference between them so you get no records.
To me thats a bug in your code
Filter(
colCalendarFilter,
DateAdd(
_firstDayInView,
ThisItem.Value,
TimeUnit.Days
) >= Start
&& DateAdd(
_firstDayInView,
ThisItem.Value,
TimeUnit.Days
) <= End
)
If these suggestions help resolve your issue, Please consider Marking the answer as such and also maybe a like.
Thank you!
Sincerely, Michael Gernaey