SQL Server Agent Job Next Run DateTime Stuck In The Past
This happened because you did a mass disable and then re-enable by updating the enabled flag in msdb.dbo.sysjobs after a massive outage; instead of doing things the right way and using the stored procedure,
sp_update_job. 

All of the jobs that were enabled one-by-one via the GUI worked fine, it was just those mass enabled that were a problem. Doing a quick disable then enable resolved all the issues. 

See link for further info: 
https://docs.microsoft.com/en-us/sql/relational-databases/system-stored-procedures/sp-update-job-transact-sql?redirectedfrom=MSDN&amp;view=sql-server-ver15

Syntax:

EXEC dbo.sp_update_job  @job_name = N'[Your Job's Name HERE]',  
@enabled = 0 --- This disables, set to 1 to enable;


Don't update system tables directly next time.