AErender in AE17 (2020) says its done immediatly - but its not

We have an application that leverages After Effects' render only mode to generate media. Prior to After Effects 2020, we could send an aerender command and wait for the process to report back that it was done, at which point the media would also be available. While testing After Effects 2020 on our application, we noticed that AE seems to report back that it's done before it actually executes the rendering command. Seeing as our application could potentially dispatch render commands sequentially and After Effects can't render more than one comp at a time, we can no longer assume that After Effects is ready to receive another command when our application receives a response from aerender. Are there any changes to aerender that we could leverage?

Basically, AE seems to report that it received the job instead of it finishing the job. We need a way to find out if AERender is done rendering its task.

Any help is much appreciated.
Cheers!