Wordpress website displaying OLD content... sometimes

Context: I have a WordPress site on Bluehost with a theme by Thrive. I set the 'homepage' to a Landing Page that I'm dubbing id 51 (post id is 51). We launched the website with a new Landing Page (id 399). This page is completely fresh, new title, new content, new everything. I changed the "Front Page" or "Homepage" in the General > Reading to this new LP. Everything seemed to be flawless. I deleted the old page (moved it to trash, but never emptied it). This same day, we noticed that when we type in our URL on this nice MacPro on Chrome, everything is fine; however, when browsing to the same URL on, say, Safari, it somehow pulls up that old content--deleted content.

I'm clearly not knowledgeable, but I can get into and investigate things:

So far, I've tried:

  • clearing individual browser caches from a visitor's perspective. Unsuccessful.
  • Purging All from the cache within WordPress This appeared to work for maybe 8-12 hours before we discovered the browser went BACK to the BAD/OLD content. I will say, by Default, I believe Bluehost has that cache level set to 1, maybe? Assets only? 2 months ago, I set it to 3 with performance in mind while building out the website. Could be storing there? ...but I PURGE it, and it returns later... That doesn't compute in my computer. Now, I've set it to 0 and the issue is currently gone, but I'm not gonna hold my breath.
  • I restored the old page, id 51, from the trash, and tried renaming the slug hoping it wouldn't find it, haha. Then, I even imported the correct, modified theme template from post 399 to post 51 hoping I could just treat the wound rather than solve it. (Thrive has an "architect" feature for WYSIWYG building so I kinda cut and paste.) This appeared to work temporarily as well.

  • My next step was to dive into the database. I've gone through the entire thing, even unrelated website databases on my host through phpmyadmin. I can't find a single reference to the old title, slug, or its content. post id 51 has my updated information as well. In fact, it's showing all of the corrected content from when I overwrote it.

All that said, The page is totally fine, and ALWAYS fine on Chrome, but Safari browsers seem to work for a while, then revert to this pesky page. I don't know enough about how a page loads to trace 1) why it loads incorrectly on a particular browser, and 2) where it would even pull outdated, DELETED content/data from to begin with...

I just feel like I broke something, and currently, am praying to the WordPress gods that 0 caching will permanently solve this ghost-site issue...

I'll update this in a few days if the problem stays away, or sooner if it persists. Hopefully, someone can point me in the right direction. Sorry for the lengthy novel. Trying to be detailed as this is my first post and I wanna be as detailed as possible as I'm just not knowledgeable enough... Thank you.