D Stanley's answer accurately explains the behavior of a put's price in relation to the price of the underlying and his graph demonstrates its non linear behavior. However, there's more to this story.
The short answer is that the brick wall that you ran into was an implied volatility contraction.
Option price is based on 6 variables: Stock price, strike price, volatility, time until expiration, current interest rate and dividend (if any) - with dividend and interest rate being minor factors. The strike price is fixed and in the short term, day to day time decay is minimal. So that leaves two main factors, price and volatility.
When there is pending news, demand for options drives option premium up. This is reflected in the implied volatility. After PANW's last earnings report, its average IV for all options was in the high 20s where it stayed until a month ago when it started rising on its way to the high 60s. You can view this at IVolatility (free sign up) at:
What does this mean for you? Strap on your seat belt.
I don't know what price the PANW was when you purchased the put so all I can do is be in the ballpark. At yesterday's closing price of $215.32, at yesterday's IV, your put was worth $2.20. Last night PANW reported earnings and it was taken to the cleaners today (down over $15 intraday). Average IV contracted to 34 today, most likely on the way back to the high 20s. A valuation at yesterday's price with today's IV means that your 6/07 $195 put was really worth only 15 cents. Due to the extreme IV expansion, it was $2.05 higher. Essentially, you paid through the nose for something worth a lot less.
Now let's factor in the price drop to today's pricing. At an IV of 34, the 6/07 $195 put should be worth $2.10 today at $200.32 which is in line with your observation.
IOW, the put's price contracted $2.05 due to IV collapse but expanded $1.95 due to the $15 price drop for a net loss of 10 cents.
The reason for the difference in my numbers ($2.20 vs $2.55) for the put is that IV is not static during the day of the earnings announcement. It was probably higher (73-ish) when you took your position.
The lesson? Buying high IV options just before a significant news release (like earnings) is an exercise in futility. IMO, if you're going to dabble, sell some inflated premium to offset the inflated premium that you buy - for example, spreads.