The phrase "although not obvious" is correct and usable in written English.
It can be used to introduce a statement that may not be immediately clear or apparent to the reader.
Example: "The solution to the problem is effective, although not obvious at first glance."
Alternatives: "even if it's not clear" or "despite being unclear".
The emotion, although not obvious, is there below the exterior.
Although not obvious, the level at which the problem is caused is not the hand, but the brain: its capacity to control movement is impaired.
Although not obvious in the early days, it gradually became clear that Silva was behind this new approach.
Although not obvious, there is a direct solution for and.
Although it is not obvious to people who are already signed up, joining Twitter is a confusing experience.
Although it was not obvious at the time, for all intents and purposes the war ended with the death of Empress Elizabeth in January 1762.
It is quite another to bake a cake from them.Part of the problem, although it was not obvious at the time, was outlined in a paper published mere weeks before Mr Miller's.
As a member of Rosoideae, strawberries have achenes, although this is not obvious to the casual observer, as they are tiny and occur on the surface of the enlarged flower axis, or receptacle.
It was a sharp piece of work by Matt Prior that removed the bails with the batsman stretching forward and after considerable scrutiny the third umpire, Asad Rauf, deemed him to be out of his ground, although that was not obvious to most observers.
The literature also suggests positive affordances of skilled diasporas and cultural diversity in the skilled workforce more generally, although it is not obvious how to target these directly.
As a result, Alternate Reality: The City is barely half a game in the traditional sense, although it's not obvious at first.
