I compared your files with mine, and see no major differences. I updated a few plugin/dependency versions, but that didn't seem to help.
My issue is that the plugin activates, but the run function is never hit. Does yours run?
EDIT: Oh, I think it has to do with my cron-expression. I was using " * * * * * * " and never saw it run. Then I changed it to "0 * * * * ?" and then I saw it running. I guess I didn't understand how cron expressions work.