I have multiple simple macros that activate specific applications, or hide them if they're already active. The activate function is timing out on me when the application is hidden. It works if the application is not yet running, and it works if the application is simply not foremost. But not when it's hidden. I note that this behaviour exactly coincides with my installation of macOS 15.0.1. I'm using KM 11.0.3.
The Activate a Specific Application action will ask the system to activate the application, and then wait for it to become active.
If the application does not become active (eg it is a background only application for example), then the action will wait and eventually time out. If you want to avoid this, you can set the timeout time to something very small and turn off notification/abort on timeout.
As the screenshot shows, the applications where I was encountering this behaviour are not background-only.
I adopted these types of macros from YouTuber Ben Vallack. I have about 20 of them for my most commonly used applications, and I use this set of macros literally hundreds of times per day. When Activate a Specific Application works, it works instantly, so it was immediately apparent when all of these macros started timing out on this action as described in my original post.
After I updated to macOS 15.0.1 and started encountering this issue, I restarted my machine, and later shut it down and turned it back on, with no improvement. The good, if mysterious, news is that sitting down this morning (machine was just sleeping overnight) I find that the activation action is again working as expected. Perhaps there was some process interfering with the activations, though I have no idea what it might be. I wasn't doing anything unusual.
So anyway, I'll keep an eye on it. Thanks for the responses.