Do you have a situation when all of your blocks lose align option? And you don’t see this in toolbar of blocks?
WordPress doesn’t have this in documentation but to make this option to work, your template must have Inherited width on parent element for your content or on content block
So, if you lose this option on Page template, then, edit it in Site editor and make sure that this option is enabled on your content block.
Sometimes, I saw that even if it’s enabled, it can be lost. Then, simply resave Page template and this should fix it