I just saw 8.2.15 in the download folder, and installed it on an Android 12 phone.

Despite being set to run 4 tasks (which is recognized in settings and listed in the Event log), it's currently running just one Asteroids task (plus Wuprop) out of several Asteroids, Einstein, and WCG tasks.

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https://boinc.berkeley.edu/dl/

Host List (via WUprop)

So after some "testing":
WUprop and Asteroids will run, but if Boinc .15 switches to Einstein or WCG (or both), they'll run for about 6 seconds, then those tasks will effectively pause, not even switching back to Asteroids after 1 hour. Any Asteroids still running will continue to run.

Forcing the Asteroids tasks to run (since they still can run) essentially requires "deleting" any non-Asteroids tasks. (Admittedly, I haven't tried suspending Einstein or WCG to see if it forces Asteroids.)

---

https://boinc.berkeley.edu/dl/

Host List (via WUprop)

Your problem is most likely related to a recently reported BOINC GitHub issue 7146:

Don't used more than xx.xx of swap space
* Describe the bug:
I upgraded my Android phone to the latest BOINC version 8.2.15 and now can only run 2 of 3 tasks concurrently on World Community Grid or Einstein.

Edit to add ~~~
The only workaround seems to be uninstall 8.2.15 and reinstall your previous working version.

The only problem doing this is you will loose all tasks in progress on the phone and have to reconfigure all your settings in the app.