Hangfire job remain in enqueued

I am using HangFire with SQL server 2012.
I recetrly come up with issue where whatever job come it get stuck in to enqueued state.
I tried lot’s fix like restart hangfire, rebuild indexes, Increase Connection.
But other try which work is, I simply create new DB for HangFire and bingo, this start working.
So what happen to that old database? the LOG is not showing informatin except below.

Error occurred during execution of 'Worker #3f7bdf63' process. Execution will be retried (attempt 2 of 2147483647) in 00:00:04 seconds.