Hello,

I looked at the LTC address you linked earlier in the post, so I hope that is the same address you are using. The pending balance seems to be still unconfirmed amounts that haven't exchanged yet. As LTC is currently up ~26% of its daily 24hr value it appears pending balance graph representation is adjusting to that value for each found block percentage that you were a part of as your earnings are confirmed for exchange into LTC.

Once each share reward is actually exchanged into LTC it will appropriately be added to your total balance. Another factor is that when pending balances are confirmed, the line for that pending graph stagnates and the actual blue balance line rises as is shown on your wallet page because those balances are no longer pending but now are confirmed and ready for payout. Also it appears as though you stopped mining using the sha256 device as that hashrate abruptly dropped, so naturally there are less earnings in a graph representation because you are using less devices.

Hopefully that answers your question, but if you would like to know more please let me know.