Getting hot roots from 10vol developer! Advice?

[Zeldacake]

Hi! I’m an aesthetician, so I’m not super familiar with hair color, however I’ve been using Pravana Chromasilk 3N and Pravana 10vol developer on my roots for years with no problems. However, I’ve suddenly been getting hot roots for the past year. The hot roots are subtle until I’m in strong sunlight, and it seems to only effect my new growth. I have medium brown hair with a 30% gray naturally. I’ve attached a photo of the hot roots for reference.
I am ready to switch brands, though I’m not sure it would make a difference! That’s why I’m here, to see if any experts have ideas of what else might be going on that would cause these hot roots! I know that 10vol developer isn’t supposed to lift, so I’m stumped! Any advice/favorite brands to switch to are greatly appreciated!
I’ve talked to several hair dressers and these are the different things I’ve tried with no success over the past year:

Prep:
-neutral protein filler treatment prior
-neutral protein filler in the color mix
-neutral protein filler applied directly to hair prior to coloring
-hair wet prior to application
-hair dry prior to application

Processing time:
-have tried 30mins
-have tried 45mins

Ratio:
-1:1
-1 color :1.5 developer

Developer:
-have tried 10vol
-tried 20vol when a hairdresser thought I might need it to open cuticle further

 

[AcidPerm]

Sorry, we can’t provide technical colour advice to an untrained dabbler. It’s against the Forum rules and is potentially dangerous.