Trichs Just Not Turning Amber

My Romulan x Diesel plant is about 8 weeks into flowering. I had some other plants that were about the same age which have completed already, however on this one, the pistols and trichs just wont turn from white/clear to amber/amber.

It did have an issue with leaves curling under, however I flushed it, and added new topsoil (it's hard keeping the PH perfect for that long).

Is there anything that would delay the final ripening?
 
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