I have same problem. I use 20 second delay for miner to start after reboot. You will find this option in control panel. Also make sure ur zone setup for RPI match the time shows in minera dashboard.
Can you run Minera with up to 5 Bades? I mean the dashboard works with up to 5 Blades?
LOG:
[2014-05-20 13:37:21.9165] 5: Dispatching new work to GC3355 cores (0x5a9118db)
[2014-05-20 13:37:21.9266] 1: Dispatching new work to GC3355 cores (0x5a9118db)
[2014-05-20 13:37:22.3161] API: Client 127.0.0.1 connected
[2014-05-20 13:37:22.4189] API: Client 127.0.0.1 connected
[2014-05-20 13:37:22.4434] API: GET: stats
[2014-05-20 13:37:30.4123] 4@21 838MHz: Got nonce 866f8d6a, Hash <= Htarget! (0x5a9118db) 70.2 KH/s
[2014-05-20 13:37:30.4151] 4: GC3355 40-chip G-Blade Miner cannot be autotuned
[2014-05-20 13:37:30.4749] Accepted 866f8d6a GSD 4@21
[2014-05-20 13:37:31.5005] 8@0 838MHz: Got nonce 000a62f7, Hash <= Htarget! (0x5a9118db) 70.5 KH/s
[2014-05-20 13:37:31.5030] 8: GC3355 40-chip G-Blade Miner cannot be autotuned
[2014-05-20 13:37:31.5625] Accepted 000a62f7 GSD 8@0
[2014-05-20 13:37:33.3936] 4@29 838MHz: Got nonce b9a5fb42, Hash <= Htarget! (0x5a9118db) 70.4 KH/s
[2014-05-20 13:37:33.3964] 4: GC3355 40-chip G-Blade Miner cannot be autotuned
[2014-05-20 13:37:33.4569] Accepted b9a5fb42 GSD 4@29