Leveraged ETF Fill Spread

I have recently purchased some 3x leveraged S&P 500 etf ($UPRO) through a limit order of 8 shares at $98.83. In my activity and orders tab it says the order was filled at $98.8299. However, when I go to my open positions, it says I have an average cost basis of $99.23, when price never even reached that level ? Also, my open Daily P/L reflects the cost basis of $98.83, and the TOTAL P/L reflects the cost basis of $99.23. What is going on here?