Ainda que mesmo no início os problemas fossem aparentes.
No entanto, desde o começo os problemas eram visíveis. yet
Learner's definition of YET
— used to introduce a statement that adds something to a previous statement and usually contrasts with it in some way
We thought the idea sounded tempting, yet [=but] common sense told us it wouldn't work.
She designs simple yet [=but] elegant clothing.
She played well, yet she didn't qualify for the finals. [=although she played well, she didn't qualify for the finals]
Everyone seemed pleased, and yet I had the feeling that something was wrong.
Source: the free dictionary