it looks like a bug where the old tasks are not executed. can you please create separate bug?
I created a new ticket tasks scheduled in the past are not running as expected · Issue #4652 · matomo-org/matomo · GitHub
edit:
ooohhhh great news (at least for me)
tseur in https://dev.piwik.org/trac/ticket/4612#comment:10 was right when he says:
"It should be triggered at some point when visits are tracked."
now all tasks seem to run again!