Elliot,
I think I narrowed my issues down to WP Engine. I’ve been troubleshooting for a while thinking it was an issue with ACF Pro, as I was having issues even when the Twenty-Fifteen theme was active and the only active plugin was ACF Pro.
As I mentioned before, downgrading to WP 4.0 from 4.1 seemed to resolve the issue, but that’s not an ideal long-term solution. So, for the short-term, I downgraded to 4.0 then cloned the site to WP Engine’s staging server where I could continue to troubleshoot.
Once cloned to their staging server, I updated WP to 4.1, assuming it would bring back the issues I was having so that I could use SCRIPT_DEBUG to narrow down the issue further. However, once upgraded to 4.1 on the WP Engine staging server, everything seemed to work fine. I cloned the staging site back to the production environment and the issues came back. . .so, I’ll be opening a ticket with WP Engine to see what on their end is causing trouble.
When I use SCRIPT_DEBUG on their production environment, I don’t see any errors in the console. . .but when I turn off SCRIPT_DEBUG, a lot of things that rely on JS in the admin fall apart.
Thought this might be helpful in case any of the other folks having issues are also on WP Engine.
I’m having issues since updating to 5.1.7.1 as well. From what I can tell, it’s a conflict with the latest point release of WordPress.
I wasn’t able to edit any custom fields at all, so I did the standard troubleshooting of de-activating plugins and themes and when I had the “twenty-fifteen” theme active and the only plugin active was ACF Pro and I still couldn’t edit fields, I tried reverting to ACF Pro 5.1.6 and still no luck. I went back to 5.1.4 which I know 100% didn’t have issues on my site, but still no luck.
So, I re-activated my theme and all plugins I had active, updated ACF to 5.1.7.1, but this time I reverted WordPress core back to 4.0.1, and all is well.
So, something in WP 4.1 seems to conflict with ACF Pro (as far back as version 5.1.4 according to my tests).
The .js error I noticed was:
load-scripts.php:563 Uncaught TypeError: undefined is not a function
But there didn’t seem to be any helpful info in the console to help me troubleshoot further. . .
I was able to get this working for ACF Pro 5.1.4.
Here’s the input.js file after making my changes:
https://gist.github.com/jasonbahl/f416856945bb98bae512
I haven’t tested with any version of ACF other than 5.1.4, so there might be some backward compatibility issues.
I also had to change some code in widget-relationship-field-v5.php to accommodate some changes to CSS classes, etc for the list items to render correctly.
See that file here:
https://gist.github.com/jasonbahl/6efc490d87bf4a4656d8
