I have had a look and the spot in PRT Premium and IG are two different products

You can see the prices are different, the PRT Premium data gaps a lot and using stochastics as an example the indicators that are used for triggers are therefore different when calculated

I have contacted PRT to see about using Premium on IG data but I will probably have to wait for IG to take version 11 in order to perform longer back tests and use the cool V11 features