Visa problems can affect both travel plans and eligibility, so they should not be treated as a simple admin issue. A refusal may affect whether the trip can begin. A delayed visa may affect dates, and a revoked or expired visa may affect whether cover can continue in the same way.
The right approach is to explain the visa event clearly and attach formal evidence where possible. Support usually needs more than a short statement such as “my visa failed”.
Because visa status can affect eligibility itself, this is a category where early communication is much better than waiting.