This issue is occurring with the deployment level "Rebuild VMs" PUT method, which is a single selector for multiple VMs in the deployment.
Aria Automation 8.17.0
The issue is with the PUT method which is used to replace a resource in its entirety, vs using a PATCH method which instead will only perform a partial update of the resource.
The Day 2 operation can be performed at the resource level instead. Multiple "Rebuild VMs" operations can be performed at that level in parallel to achieve the same effect.
A fix for the deployment level operation will be added to the master branch where the PUT request will be converted to a PATCH request instead.