Separated, grainy ganache (Dark and Stormies from Grewelings's book)

Separated, grainy ganache (Dark and Stormies from Grewelings's book)

I tried making "Dark and Stormies" out of Greweling's book (Chocolate and
Confections). The center is a white chocolate ganache infused with vanilla
and ginger and with rum. Both times I tried it, the ganache came out
grainy or almost spongy in appearance.
I've never had this problem with ganache (although I'm aware that it is
very common). I've also never used Greweling's technique for ganache. It
has two primary differences:
The chocolate has to be tempered prior to using it for the ganache.
The chocolate is melted at 86 F (for white chocolate) before the cream is
added.
Normally, I would use chopped up unmelted chocolate and pour hot cream
over it. I wanted to try Geweling's method, though.
Attempt 1:
I know the chocolate was over heated (probably to around 130-140) during
tempering, but the chocolate didn't show any signs of burning.

Attempt 2:
This time the chocolate was kept at the right temperature. I also stirred
the ganache slightly less. The result seems to be better, but still
separated.

Thanks!