"Confirm Subscription" interactive button fails silently

[strachg]

Mattermost - 6.0.1
com.mattermost.aws-sns - 1.2.0

Custom EKS deployment

Using the user with appropriate privileges (i.e. id added to Authorized User IDs), selecting the Confirm Subscription button on the alert in the specified mattermost channel doesn't have any effect. No log entry is made to say that it failed or succeeded.

From the mattermost container output I can see the log entry for receipt of the new subscription request from AWS but I'm unable to confirm it via mattermost.

Workaround as this stage is to copy the subscriptionURL from the debug log and paste it into a browser ( possibly also a curl would work ?? didn't test that )