Rule reminder
Any concessive structure can often be rephrased using a different connective: noun phrase ↔ subjunctive clause, pur + gerund ↔ sebbene/nonostante + subjunctive (same subject), anche se + indicative ↔ sebbene + subjunctive. The key is to change the verb form correctly when switching connectives.
Trasforma con "pur + gerundio": "Sebbene capisse il problema, non sapeva come risolverlo."