I have a SharePoint list with 1500+ items in it. I am using this list for ComboBox in another list's Single-line Text field Column in the Form. Searching, Selection, and Default value result displays. But all items not showing in the ComboBox's list result (Some random items missing in the ComboBox but present in the SharePoint list).
I have created two collections
ClearCollect(CollectKunde,Kundenstammliste.field_1);
Clear(KundennummerChoice);ForAll(Filter(Kundenstammliste,field_1=ComboBox1.Selected.field_1),Collect(KundennummerChoice,Title));

I have added ComboBox in the SigleLineText Filed's DataCard to save selected values in this field. Values saving in the list. and also Showing Default selected value in the ComboBox's search field.
Properties of ComboBox1 are as follows:
Items = //Kundenstammliste.field_1
CollectKunde
DefaultSelectedItems = If(SharePointForm1_2.Mode=FormMode.Edit||SharePointForm1_2.Mode=FormMode.View,[DataCardValue14_2.Text])
/*If(SharePointForm1_2.Mode=FormMode.Edit||SharePointForm1_2.Mode=FormMode.View,{'@odata.type':"#Microsoft.Azure.Connectors.SharePoint.SPListExpandedReference",Id:LookUp(Kundenstammliste,field_1=DataCardValue14_2.Text,ID),Value:DataCardValue14_2.Text})*/
OnChnage = //If(SharePointForm1_2.Mode=FormMode.New,KundennummerChoice,[DataCardValue22.Text])
Reset(ComboBox1_1);Clear(KundennummerChoice);ForAll(Filter(Kundenstammliste,field_1=ComboBox1.Selected.field_1),Collect(KundennummerChoice,Title))
DisplayFields= ["field_1"]
SearchFields= ["field_1"]
Dropdown field
Searched Item in the SharePoint List
Showing resultant list as per search text
Getting blank results for some values.
Is there any items limitation for the ComboBox collection?
Any solution to reflect all values from the SharePoint list into the ComboBox?
Thanks in advance!