Your thumb is too high when indexing on your drawstroke and it's driving the web of your hand too far up. A larger memory bump won't solve this issue, because you're not making firm contact with the bottom of the grip safety (where all the leverage is to deactivate it).
I dug out my 1911 airsoft trainer. Which, unfortunately doesn't have a functional grip safety, but I'll show you what I mean.
If you start with the thumb high on the back of the gun like this during the drawstroke:
You can end up without engagement of the grip safety if you curl the thumb down to hit the thumb safety (see the gap between my palm and grip here):
Try it a few times and you'll see how positioning the thumb that high on the draw stroke more often than not ends up with less grip safety engagement.
Instead, try starting your thumb a bit lower, along side the hammer:
Then as your draw clear from the holster, you just slide your thumb onto the top of the thumb safety:
Which will give you full engagement of the grip safety and position you onto the thumb safety nicely: