I’m going to guess that collapsing action groups did not get higher priority like multiple tags, batch editing, new repeat, new notifications and did not make the cut for version 3.0.
It looks like a pretty good bet that it will appear in version 3.1. It’s not in the 3.0.4 TestFlight (yet). Crossing my fingers that it makes it in the 3.0.4 cut.
There are so many features just yelling for attention that it’s hard to know which ones are louder. The Mac TestFlight and the web site sounds like it’s getting the main focus right now.
You can always e-mail firstname.lastname@example.org to upvote for this feature and tell the Omni Humans that this is an important feature to include sooner rather than later.