It is easy for English speakers to get the absentive aspect confused with the English progressive, (“is verbing”) which is very similar in structure!
Remember, that in German sein(to be) + infinitive expresses absence, not just a continuing action. You’ll need to add an extra word like “out” or “off” or “away” to the English translation to capture the full meaning!
Er ist lernen.
He is out / off / away studying.
❌He is studying.
There are a few different ways to express the progressive in German, but probably the simplest is to use beim or am before a verb turned into a noun. Notice the difference between this structure and the absentive aspect:
Karin ist am / beim Einkaufen.
Karin is shopping.
Karin ist einkaufen.
Karin is out shopping.

