I don't know why it does that, @plumey, (you may have got an answer to your question somehow, but I'll go ahead and add some thoughts here just in case) other than it's happened a few times over the last 15 months, and periodically gets older transactions wiped while leaving a few days. It must be something Steemit is doing, and for whatever reason, they want the wallet cleaned out. There are other ways to get the information, just not as convenient. I've wondered why they just either keep it all, or get rid of it, because other than claiming rewards, it doesn't really serve much purpose if they purge everything. They could leave the top part with the balances and get rid of the transaction history.