I am also having this issue. I thought I had fixed it by disabling Gutenberg (using a plugin) but it’s back. It breaks Pagination too on my side, as well as makes it impossible to save in the composer.

Have: disabled every plugin, cleared caches

2. Do you have Optimise CSS Delivery enabled in whatever caching program you use? Enabling that in WP-Rocket made my social icons completely white out and caused other problems.

If you do have any CSS minify/related settings on, try disabling them and see if it makes a difference.

How I’ve fixed it permanently (I think).

Bought WP-Rocket -> activated separate mobile caching

Simple as that… shame it cost me $49 for a one-year license but for all the recommendations by staff here of WP Super Cache, WP Rocket with its separate caching for mobiles is the only thing that has fixed the desktop/mobile problem.

I agree, but after two days of trial and error this was the only way I could fix it, by disabling the ‘Cache Everything’ page rule for the entire site. 🙁

Here’s how I have fixed it, although not ideal.

Are either of you guys using Cloudflare? I found disabling ‘Cache Everything’ on the entire site made the problem go away, even if other caching plugins are installed.

It seems some sort of caching issue makes the site confused about which theme to show – possibly because they are from the same files/design?

Obviously this is not ideal because Cloudflare is important for many sites.

There needs to be a permanent fix for this because reading the forums a lot of people have been affected by it.

Well, it seems the ‘mobile theme showing on desktop’ problem is still here, even if some other problems have gone away. It has to be caching related or something in the code, but I’ve followed every instruction…

Okay, I think I may have fixed this… but will give it 24 hours until I’m sure.

I downloaded the Disable Gutenberg plugin and it fixed everything so far. The wrong version showing, posts not posting, ‘Load more’ not loading, previews not previewing.

Gutenberg is a horror story but I didn’t realise how much damage it could do.

I’m having problem number two as well. The mobile version randomly appears on desktop and sometimes vice versa. I try clearing cache without any real results. Not sure if it’s Cloudflare related. I have followed the WP Super Cache recommendations from this site.