This is solved, thank you @stu1811. I expected to be able to set this through the “Configuration” UI in HA, but apparently this functionality is not exposed there.
I had to “Manage Zigbee device”, the select the cluster and set the value. I had tried this previously but it didn’t work, but as @stu1811 pointed out, the max level is 254 and I had entered 255. Link to video on how to change cluster parameters, although current HA menu location is different.