I think the 100% POS interest accounts for compound interest because I am not receiving the 0.27% per day that 100%/365 days in a year would bring. This means that for the interest it will be harder to accumulate in the first few months with most coming in the later months.
Like the other guy said he is earning stake every 48 hours, I think this could be the reason. But we could get a comment from the dev.
POS is working fine here... I have had no problems staking with any version of the supercoin wallet...
Have you tried consolidating your coins?
Coin consolidation in wallet
1. Enable Coin Control
Go to Settings\Options\Display and check the Display Coin Control Features checkbox.
2. Create a new address to receive coins.
Select Receive Coins, and click New Address. Copy the new receive address.
3. Send Coins
Click Send. Click Select Inputs. Select all the inputs you want to consolidate into one transaction.
Send coins to new Receive Address you created in step 2.
This consolidated batch of coins will now stake in larger amounts, instead of giving you a lot of tiny dust payments.
Since the POS interest payments also stake after 1 day, and begin paying POS on previous POS deposits, (go compound interest!) the deposit consolidation may need to be done monthly.
Since Supercoin only needs 24 hours to stake, the consolidation only cost 1 day of POS payments.