broadcasted transactions not included on chain

[0xluk]

A client reported that 5-10% of daily broadcasted transfer transactions(40-50 transactions from which 5-10 were not included) are not included on chain.

The following scenarios were excluded:

• broadcast-transaction endpoint returned 200 which means tx signature was valid (was confirmed with our logs)
• source id had enough balance
• target tick not empty
• tick offset is high enough (15)
• client broadcasted another transaction after the previous one from the same source id was included

The following replication tests were conducted:

• broadcasted 40 transactions on epoch 123 over 4 hours, one each 6 minutes; 2 of them were not included but their target tick was empty/incomplete which does not fall of in our case
• broadcasted 40 transactions on epoch 124 over 4 hours, one each 6 minutes; all of them were included
• broadcasted 144 transactions on epoch 124 over 24 hours, one each 10 minutes; all of them were included