Check these in order: (1) whether the New Builder is turned on for that page — when it's enabled and its Published toggle is on, the classic modules are ignored in favor of the builder layout; (2) you edited the right item — pages and blog posts can have similar titles but are separate records; (3) a browser cache — open the page's Preview link in a private window; (4) for blocks with Hide On Desktop, Hide On Tablet or Hide On Mobile ticked, the block is intentionally hidden on that device size.