If your Dallas DS18B20 was purchased on ebay or amazon or elsewhere other than DigiKey, Mouser, etc, it is likely counterfeit and will not work in parasitic power mode and will give a -127.

Here's a sketch to help determine of the Ds18B20 is genuine and rule-out shoddy counterfeits:

https://github.com/cpetrich/counterfeit_DS18B20

I wasted countless days and days with remote sensors only to find they were counterfeit.