I am solo mining so fast, the problem is on the pool.
I tried the pool like 1 hour, I didn't find any block.
Then I switched to solo and now finding a lot of blocks.
C'mon, try it !!!
No rejecteds for me... just "New block detected on network" and several seconds/minutes: Found block.
Good luck !
The issue appears to be with the coind; debugging it at the moment, but I'd do what this man says, solo it'