What could be causing this ? Possibly slugs having a chomp too? It was repotted recently but no improvement.
Grow in sun or semi-shade in fertile, well drained soil. Cut back after flowering.
By division. By seed (although plants will not come true to form). Will self-seed.
Pests, diseases or disorders
Powdery mildews, aphids, Aquilegia downy mildew.