Hi PowerApps community,
I've made a canvas app, with a gallery filtered by three combo boxes. The data source is a Collection filled by a Dataverse instance.
The image below, shows the app when i open it the first time.

This is the ITEMS selection FX of the gallery.
If(IsBlank(ComboBox1)
&& IsBlank(ComboBox1_1)
&& IsBlank(ComboBox1_2),TempCompetences
If(Not(IsBlank(ComboBox1))
&&Not(IsBlank(ComboBox1_1))
&&Not(IsBlank(ComboBox1_2)),
Filter(TempCompetences,Person.Person exactin ComboBox1.SelectedItems.Person,Product.Product exactin ComboBox1_1.SelectedItems.Product,Value.Value exactin ComboBox1_2.SelectedItems.Value),
If(Not(IsBlank(ComboBox1))
&&(IsBlank(ComboBox1_1))
&&(IsBlank(ComboBox1_2)),
Filter(TempCompetences,Person.Person exactin ComboBox1.SelectedItems.Person),
If(Not(IsBlank(ComboBox1))
&&Not(IsBlank(ComboBox1_1))
&&(IsBlank(ComboBox1_2)),
Filter(TempCompetences,Person.Person exactin ComboBox1.SelectedItems.Person,Product.Product exactin ComboBox1_1.SelectedItems.Product),
If(IsBlank(ComboBox1)
&&Not(IsBlank(ComboBox1_1))
&&(IsBlank(ComboBox1_2)),
Filter(TempCompetences,Product.Product exactin ComboBox1_1.SelectedItems.Product),
If(IsBlank(ComboBox1)
&&(IsBlank(ComboBox1_1))
&&Not(IsBlank(ComboBox1_2)),
Filter(TempCompetences,Value.Value exactin ComboBox1_2.SelectedItems.Value),
If(IsBlank(ComboBox1)
&&Not(IsBlank(ComboBox1_1))
&&Not(IsBlank(ComboBox1_2)),
Filter(TempCompetences,Product.Product exactin ComboBox1_1.SelectedItems.Product,Value.Value exactin ComboBox1_2.SelectedItems.Value))))))))
below the image after selection.

Below an image after deselection

The initial selection works fine, but when i deselected a item, no results are displayed. What can i do to fix this?
All help is appreciated.