Could you experiment with the testnet? It's less expensive than to mine blocks on the livenet which get rejected for some reason. There are two active testnet nodes at seed1.orbitcoin.org:25298 and seed2.orbitcoin.org:25298
Start the daemon with debugging on and look at debug.log to see why it rejects them actually.
I'll try some yeah.
Haven't had time to test on testnet, but FWIW, I installed and tested PXC and was able to generate blocks just fine without submitblock enabled.
Not much is even showing up in the orbit logs...
This is the stratum logs (submitblock disabled, txmessages enabled)
20:11:46: ERROR: rpc_do_call: coind:5790 500
20:11:46: ERROR Orbit Invalid mode
20:11:46: *** REJECTED
Orbit 4055
20:11:46: block 02000000bca041e0ac111c7290a53767cdcde31898b788fd2134d52f8b3fb2ae0aea09eb2aec96e
168b1e700f4dc2f997817fca507ad2e7cfe94e93911f8adfeb88c7002c624a4563a1b3b1e000dee
ea0102000000c624a45601000000000000000000000000000000000000000000000000000000000
0000000ffffffff1d02d70f062f503253482f04b424a4560881004290000000007a706f6f6c0000
00000140420f0000000000232103e417aed9e859978a89e36a094ce558f9a118efb2f73b76ec2c2
03439720b0d30ac0000000000
20:11:46: --------------------------------------------------------------
20:11:46: submit 95.156.52.70 13700, 00000000, 56A424C6, 4000310B
20:11:46: 1532b6d108d7db7d actual
20:11:46: 3fffc00000000000 target
20:11:46: 3b1b39fffffffe00 coin
20:11:46: ERROR: rpc_do_call: coind:5790 500
20:11:46: ERROR Orbit Invalid mode
20:11:46: *** REJECTED
Orbit 4055
20:11:46: block 02000000bca041e0ac111c7290a53767cdcde31898b788fd2134d52f8b3fb2ae0aea09eb8f2f2da
f4a982ba4d7dfba8a9b5b492c67880cf691449d3850e9eb7265a670aac624a4563a1b3b1e0b3100
400102000000c624a45601000000000000000000000000000000000000000000000000000000000
0000000ffffffff1d02d70f062f503253482f04b424a4560881003e47000000007a706f6f6c0000
00000140420f0000000000232103e417aed9e859978a89e36a094ce558f9a118efb2f73b76ec2c2
03439720b0d30ac0000000000
20:11:46: --------------------------------------------------------------
20:11:46: submit 216.48.95.60 13699, 00000000, 56a424ae, 7000d37a
20:11:46: 1b54c9c85f13b9c6 actual
20:11:46: 1fffe00000000000 target
20:11:46: 000053d799000000 coin
20:11:47: submit 71.63.90.121 13700, 00000000, 56a424c6, 4bba1500
20:11:47: 03a8b51380cf45e4 actual
20:11:47: 07fff80000000000 target
20:11:47: 3b1b39fffffffe00 coin
20:11:47: ERROR: rpc_do_call: coind:5790 500
20:11:47: ERROR Orbit Invalid mode
20:11:47: *** REJECTED
Orbit 4055
20:11:47: block 02000000bca041e0ac111c7290a53767cdcde31898b788fd2134d52f8b3fb2ae0aea09eb987389b
5f629add128dd2aef8595f72986ad1d380df336d824534a525db337a9c624a4563a1b3b1e0015ba
4b0102000000c624a45601000000000000000000000000000000000000000000000000000000000
0000000ffffffff1d02d70f062f503253482f04b424a456088100428f000000007a706f6f6c0000
00000140420f0000000000232103e417aed9e859978a89e36a094ce558f9a118efb2f73b76ec2c2
03439720b0d30ac0000000000
20:11:47: --------------------------------------------------------------
20:11:47: submit 71.63.90.121 13700, 00000000, 56a424c6, c0c21300
20:11:47: 05ff5b4c457dbae5 actual
20:11:47: 07fff80000000000 target
20:11:47: 3b1b39fffffffe00 coin
20:11:47: ERROR: rpc_do_call: coind:5790 500
20:11:47: ERROR Orbit Invalid mode
20:11:47: *** REJECTED
Orbit 4055
20:11:47: block 02000000bca041e0ac111c7290a53767cdcde31898b788fd2134d52f8b3fb2ae0aea09eb2aec96e
168b1e700f4dc2f997817fca507ad2e7cfe94e93911f8adfeb88c7002c624a4563a1b3b1e0013c2
c00102000000c624a45601000000000000000000000000000000000000000000000000000000000
0000000ffffffff1d02d70f062f503253482f04b424a4560881004290000000007a706f6f6c0000
00000140420f0000000000232103e417aed9e859978a89e36a094ce558f9a118efb2f73b76ec2c2
03439720b0d30ac0000000000
20:11:47: --------------------------------------------------------------
orbitcoind -debug
01/24/16 01:11:15 ThreadRPCServer method=getinfo
01/24/16 01:11:15 keypool return 3
01/24/16 01:11:15 ThreadRPCServer method=getdifficulty
01/24/16 01:11:16 ThreadRPCServer method=getinfo
01/24/16 01:11:16 keypool return 3
01/24/16 01:11:17 ThreadRPCServer method=getinfo
01/24/16 01:11:17 keypool return 3
01/24/16 01:11:17 ThreadRPCServer method=listtransactions
01/24/16 01:11:47 ThreadRPCServer method=getinfo
01/24/16 01:11:47 keypool return 3
01/24/16 01:11:47 ThreadRPCServer method=listtransactions
01/24/16 01:12:17 ThreadRPCServer method=getinfo
01/24/16 01:12:17 keypool return 3
01/24/16 01:12:17 ThreadRPCServer method=listtransactions
01/24/16 01:12:48 ThreadRPCServer method=getinfo
01/24/16 01:12:48 keypool return 3
01/24/16 01:12:48 ThreadRPCServer method=listtransactions
01/24/16 01:13:15 ThreadRPCServer method=getinfo
01/24/16 01:13:15 keypool return 3
01/24/16 01:13:15 ThreadRPCServer method=getdifficulty
01/24/16 01:13:19 ThreadRPCServer method=getinfo
01/24/16 01:13:19 keypool return 3
01/24/16 01:13:19 ThreadRPCServer method=listtransactions