I've been growing beefsteak tomatoes in the same raised bed for three seasons now, and every year about half of them develop that dark sunken spot on the bottom. I water pretty regularly and added some lime last year but it didn't help much.
Are you checking your soil moisture consistently, or is it more of a when-you-remember situation? Blossom end rot is almost always a calcium uptake problem, and it usually happens when watering is inconsistent - even if you think you're watering regularly, if there are dry spells between waterings, the plant can't move calcium to the fruit properly. The lime you added last year probably helped a bit, but if your soil is already alkaline enough, that's not the real issue. What matters most is keeping that soil evenly moist throughout the growing season (not soggy, just consistent), and honestly, switching to drip irrigation or soaker hoses changed everything for me when I was dealing with the same thing on my old garden. You might also try adding a calcium source like crushed eggshells or gypsum mixed into your raised bed soil at the start of the season.
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