“”The backup of this post in your browser is different from the version below.””

I can confirm this issue, which ONLY happens when ACF blocks are present. This started happening with Gutenberg 6.5, maybe even 6.4, and the issue persists until today.

Another issue that came back is the issue of ACF blocks not “registering” default field values until you make any change to a field. So let’s say you have a Heading block made with ACF Pro, and if you just insert the block and make no changes to it, and save the post/page, nothing shows up on the front end, even though on the backend, the default value is correctly shown. If you make a change to any of the block fields, then all is fine… This was happening a year ago, got fixed by springtime 2019, and Gutenberg managed to reintroduce this annoyance with Gutenberg 6.4, which persists until now…

If I would make an educated guess to why these issues are happening, is because ACF blocks are dynamic, while most blocks made with React are static…

If I create a new page, add some blocks, close it, re-open it, changing nothing, then this message is there.

Hi, James. Some logic around autosaving was fixed recently (e.g. #18051). Are you still experiencing this issue in the latest version of Gutenberg?

If so, then the following would definitely be something to look at:

I am using custom ACF Blocks, and some custom changes to Gutenberg Blocks. It seems to happen more when using ACF Blocks, but I need to look in to some more.

(emphasis mine)

Hi @nick6352683, thanks for the extra feedback.

Two quick notes on the following:

Another issue that came back is the issue of ACF blocks not “registering” default field values until you make any change to a field. So let’s say you have a Heading block made with ACF Pro, and if you just insert the block and make no changes to it, and save the post/page, nothing shows up on the front end, even though on the backend, the default value is correctly shown. If you make a change to any of the block fields, then all is fine… This was happening a year ago, got fixed by springtime 2019, and Gutenberg managed to reintroduce this annoyance with Gutenberg 6.4, which persists until now…

• This would be better handled in a separate ticket, so that this ticket can be kept focused and tickets can be easier to search in general.
• It’s important to note that these systems for change detection in the block editor are, as of WordPress 5.3, part of core and not just the Gutenberg plugin. Without having more means to debug, this really sounds like an issue to bring up with maintainers of either ACF Blocks or ACF.