1. The most important or central problem, topic, or matter under discussion or consideration
The main issue with the project is the lack of funding.
A questão principal com o projeto é a falta de financiamento.
2. The primary point of contention or disagreement in a debate or discussion
Let's focus on the main issue rather than getting distracted by minor details.
Vamos focar na questão principal em vez de nos distrairmos com detalhes menores.