view attachment images in backend

Assuming you are using the new Gutenberg Block Editor. To view the Custom Fields for any post, click the three dots in the upper-right corner of the screen and then do one of these (depending on your version of WordPress):

• For older versions of WordPress, go to Options and check the box to enable Custom Fields (under “Advanced Panels”).
• For newer versions of WordPress, go to Preferences > Panels and check the box to enable Custom Fields (under “Additional”).

After enabling, scroll down the page to find the Custom Fields meta box.

Thank you Jeff. I followed your steps, and indeed, it was unchecked. Annoying thing though is that I can check it, but that it reloads, doesn’t show the custom filed meta box, and when I check in the preferences again, the custom fields is unchecked again?? I update the advanced custum fields plugin, but that didn’t solve it. I know, this doesn’t seem to be a bug in your plugin but elswhere, but if you have any thoughts…
Does the paid version works in the same way? (I think we will swich anyway), but I need to get this solved first.

“Does the paid version works in the same way?”

I can answer this question if you want to reach us via our contact form at Plugin Planet (the forums here at www.ads-software.com forbid any discussion of pro/premium plugins).

“when I check in the preferences again, the custom fields is unchecked again??”

It sounds like something is interfering with normal functionality. It could be your theme or maybe some other plugin. To help with that, here is a troubleshooting guide that may be useful for you.