Let A =
That's where the problem lies, B =
I'm not very clear about the reason. A natural sentence would be [ A(,)
but B. ] (The comma is optional.) Some other possible alternatives with
although are [ A,
(al)though B. ], and [
(Al)though B, A.] (you need a comma after B, not after
although). You can arrange your thought in a reverse order: [ B(,)
but A. ], [ B(,)
although A. ], [
Although A, B. ]. Though it's generally not recommended, you can start a sentence with
but, but it will link the whole sentence to the previous one: [
But B,
although A. ]. —
Damkerng T. Jul 8 at 10:44