It’s actually not surprising at all that symptoms persist.
However you reduce uric acid, the result is the same: uric acid that had crystallized in the past dissolves and that often causes frequent gout symptoms for a few months and sometimes even longer. People are commonly told to take a medication such as colchicine or an NSAID daily for a couple of months in order to prevent redness, swelling and pain.
It’s not surprising that walking might trigger symptoms either. Some of these crystals are stashed away from your blood and dislodged by walking or exercise. Then they start dissolving and your immune system reacts…
Congratulations on reducing your uric acid so much by the way! You’ll have to monitor that to make sure it doesn’t creep back up.
While 5 is fine in the long run, you might benefit from temporarily lowering it a bit more (for as long as you’re suffering from gout symptoms).