SandboxedPlugin still waiting for SandboxThread to exit (maya & arnold)

Still having this issue with 10.4.0.12 And Nuke Plugin. From what I can see in these posts here it happens to any plugin. We have this with both Nuke and Arnold as well.
My two cent is that it has to do something with the weight of the job. It only happens for us if its a really heavy arnold shot or a concurrent task Nuke job.