Saw a number of threads on this issue and the consensus seems to be to blame the project. However, I noticed it only after switching to a different account manager and prior to that never observed the behavior.

Behavior:
Boinc is set to suspend on mouse/keyboard use and does not suspend all or any processes when the computer is actually in use. Particularly of interest is I'm observing one active task getting suspended for upload but the rest left alone. For a 32 thread machine like mine that means I'm still churning a lot of power and honestly I mainly suspend while in use because my room doesn't cool down at all if the computer is working on boinc tasks and when gaming I like to turn the 'scientific space heater' off for a bit x). Screenshot below to show one Asteroids@home upload process being suspended while the other Asteroids@home are still running. Never had an issue with asteroids at home while I was on gridrepublic and I've observed similar behavior with other projects like world community grid.
https://pasteboard.co/Ivp9Zjf.png

Event log entries showing it's reading the pref override file:
9/1/2019 10:34:21 AM | | General prefs: from https://www.grcpool.com/ (last modified ---)
9/1/2019 10:34:21 AM | | Computer location: work
9/1/2019 10:34:21 AM | | General prefs: no separate prefs for work; using your defaults
9/1/2019 10:34:21 AM | | Reading preferences override file
9/1/2019 10:34:21 AM | | Preferences:
9/1/2019 10:34:21 AM | | max memory usage when active: 65474.12 MB
9/1/2019 10:34:21 AM | | max memory usage when idle: 117853.42 MB
9/1/2019 10:34:21 AM | | max disk usage: 35.99 GB
9/1/2019 10:34:21 AM | | don't compute while active
9/1/2019 10:34:21 AM | | don't use GPU while active
9/1/2019 10:34:21 AM | | suspend work if non-BOINC CPU load exceeds 25%

Other possible factors:
Could possibly be that my mouse and keyboard are gaming hardware and use USB 3.0 and specialized drivers (to drive macro-keys and RGB shinies) but that's unlikely given the upload tasks are honoring requests to be suspended during user activity.

Your screenshot is broken (or empty).
You omitted mentioning your operating system, as with Linux it's possible that due to changes in the way the x-server is polled, BOINC can't make out if the computer is in use or not.
And else, always check in BOINC Manager, Advanced view, Activity menu, what your settings are. They must be "based on preferences" as when set to "run always", it will ignore these 'in use' preferences.

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The screenshot is working here, but it's on an advertising-supported website - it's possible an ad-blocker or similar might interfere with display.

I see a single task 'uploading (suspended - computer is in use)', plus many others either 'Running' or 'Waiting to run'. Most of the running tasks are from Asteroids@home, plus one Rosetta@home: the waiting tasks are Rosetta, World Community Grid, and one Einstein.

It looks as if networking is being suspended, but computing isn't. BOINC doesn't have separate 'computer in use' detection mechanisms for the two functions, so I'd zero in on the 'Activity' menu - is the top ('Run') section set to 'always' or 'based on preferences'?