I'm the user Robert mentioned.
More specifically, the option for an "In/Not In" operator is no longer available for "Owners" filters. This means I can no longer implement a filter that excludes tickets where the Owners list includes a specific named worker.
This option was available for the "Last Worker" filter in 5.0
My workaround at present is to specify a list of every worker except the ones not wanted, but this is not exactly the same thing, and a big maintenance hassle as new workers are added.
I was looking for the same thing. Thanks for adding it here. :)
Let's hope it's re-added soon!
This was reintroduced in 5.4.3