Error in CreateHostpoolTemplate.json

[GrahamHassall]

I am getting a new error when deploying a hostpool using the "CreateHostpoolTemplate.json" in reference to configuring diagnostic settings on a new host pool and application group.
The hostpool, VMs and desktop application group do deploy successfully, but diagnostic settings are not configured
The error messages are as follows (actual resource names replaced with [placeholders])

Diagnostic settings does not support retention for new diagnostic settings. (Code: BadRequest, Target: /subscriptions/[subscriptionId]/resourceGroups/[resourceGroupName]/providers/Microsoft.DesktopVirtualization/applicationgroups/[applicationGroupName]/providers/Microsoft.Insights/diagnosticSettings/diagnosticSetting)

Diagnostic settings does not support retention for new diagnostic settings. (Code: BadRequest, Target: /subscriptions/[subscriptionId]/resourceGroups/[resourceGroupName]/providers/Microsoft.DesktopVirtualization/hostpools/[hostPoolName]/providers/Microsoft.Insights/diagnosticSettings/diagnosticSetting)