Apps · The Apps window and launcher
Why does the Internal tab say "No apps match the current filter"?
Short answer: The filters are hiding them. Set Older than to All or turn off Hide running and your apps will appear on the Internal tab.
Your filters are hiding everything. The Internal tab starts by showing apps you haven't used in 30 days and hides apps that are running, so on a Mac where you use most apps often the list can come up empty.
Lower the Older than threshold (choose All) or turn off Hide running, and the apps appear.