Laravel SEO sitemap broken!

I am at my wit's end, utterly despairing over a critical Laravel SEO issue that's driving me absolutely insane. I've been pulling my hair out for hours, maybe even days, trying to fix this, and I'm completely stuck. Our entire dynamic XML sitemap isn't updating properly, despite every single effort I've thrown at it. The core problem is that our 'Dynamic XML Sitemap for Laravel' solution, which is supposed to be auto-updating and future-proof, is failing catastrophically in Google Search Console (GSC). New pages on our site are simply not getting indexed, or if they are, it's taking an eternity, and worse, old, removed pages are stubbornly persisting in the index. This is seriously, seriously hurting our Laravel SEO efforts and rankings, and I'm watching our organic traffic just flatline. Our setup is pretty standard, or so I thought. We're running a Laravel 10 application. For the sitemap, we're using a custom-built dynamic sitemap generation logic, which essentially mirrors the functionality of a robust 'Dynamic XML Sitemap for Laravel' product. Caching is handled with Redis, and we have a cron job scheduled to run `php artisan sitemap:generate` every 6 hours. Our server environment is AWS EC2 with Nginx and PHP 8.2. I've tried everything I can think of. I've manually cleared all Laravel caches – `cache:clear`, `config:clear`, `view:clear` – multiple times. I've manually run the sitemap command: `php artisan sitemap:generate`. When I check the local `sitemap.xml` file on the server, it *looks* updated, with correct timestamps and all the new URLs I expect. I've checked the cron logs, and they confirm the command executes successfully every time without any errors. I've verified our `robots.txt` file points to the correct `sitemap.xml` path, absolutely no issues there. I've even checked file permissions for `sitemap.xml` – everything seems correct, the web server user definitely has write access. The most frustrating part? I've forced manual re-submission of the sitemap in GSC multiple times, like a hundred times maybe. And GSC still shows 'Last read: [OLD DATE]', sometimes weeks old! It's like it's completely ignoring my updates. I've also checked server-side caching, like Nginx micro-caching and Cloudflare CDN, temporarily bypassed and purged them, but still, no change whatsoever. This isn't just a minor glitch; this is a massive, critical hit to our Laravel SEO strategy. New product pages, new content, they're simply not discoverable by search engines, and meanwhile, removed content that should be gone is still showing up in SERPs. I am losing traffic and potential conversions daily because of this, and it's impacting our business significantly. The urgency here is extreme. Please, for the love of all that is holy, has anyone faced this exact issue with dynamic sitemaps in Laravel? What obscure thing am I missing? Is there some hidden GSC quirk, or a server-side configuration that's completely flying under my radar? Any advanced debugging tips or server-side configurations I should check? I'm completely stuck and running out of ideas. Anyone faced this before?