i wouldn't be surprised if they set their minimum fee to something above your fee, like 100-200 satoshi/byte!
your transaction is apprently already confirmed but for future references the solution for using viabtc in case they didn't see your transaction is pretty simple
submit your transaction with them: https://pool.viabtc.com/tools/BTC/broadcast/
they too are running a node which you can push your tx to. just copy your raw transaction and paste it in the link above and broadcast it. they will see it even if noone else does.
This means that they're not dealing with transactions, sent with low fee settings?
Do they use this to filter out spam (or suspicious) transactions, or I don't know what is the reason for them.