Hi @dberardo-com, thanks for your report.

Unfortunately, I couldn't reproduce the described problem. I used the following code sample to check nodes' order:

from zabbix_utils import Sender

sender = Sender(use_config=True)

for _ in range(5):
    print(sender.clusters)
    sender.send_value('host', 'item.key', 'value', 1695713666, 30)

and got the following result:

[[["zabbix.cluster.node1", 10052], ["zabbix.cluster.node2", 10051], ["127.0.0.1", 10051]]]
[[["127.0.0.1", 10051], ["zabbix.cluster.node2", 10051], ["zabbix.cluster.node1", 10052]]]
[[["127.0.0.1", 10051], ["zabbix.cluster.node2", 10051], ["zabbix.cluster.node1", 10052]]]
[[["127.0.0.1", 10051], ["zabbix.cluster.node2", 10051], ["zabbix.cluster.node1", 10052]]]
[[["127.0.0.1", 10051], ["zabbix.cluster.node2", 10051], ["zabbix.cluster.node1", 10052]]]

So, the main point here is that the active_node is stored in the object Sender. Using a single Sender object allows you to keep the latest active_node and make the library connect to this node first.
You probably used several Sender instances that resulted in ordering cluster nodes every time from scratch.

I hope my explanation will help you deal with the problem mentioned. Whatever, feel free to create another issue if the problem still exists.