I've botched a few bases, normally scaling down, bhagaring the tomato/garlic/spices & once by cooking the blended mixture in the slow cooker for too long.
When Az from Zaal said that domestic cooker versions may take a bit longer to cook, the cynic in me said no as usual, but logically correct, it would eventually reach the same stage.

I've changed my approach a little, looking to balance the taste of spice/tomato paste with the sweet onion gravy, or even tip the balance in favour of the gravy. On the tomato side , I may salvage a poor madras at best from it. On the gravy side or if there is a middle, I've got what I've been handing over my hard earned week in/out for decades ;D
From what I can see, c2g's recipe's call for 1TBLsp MP, which is nearly double what I normally add, leading me to believe that all along it's been a taste I've been trying to get
rid ofin my curries, rather than introduce.
Acidic tomato was trumping the garlic/gravy in my failures
Edit-trumping the gravy, banjarra, masala sauce, magic sauce, south indian garlic sauce.....you name it
Regards
ELW