Is there any way to force a custom block in the Custom Block Library to invalidate cache on edit update? I have created custom blocks in the Custom Block Library and placed instances of the blocks on a page in Block Layout.  The blocks get cached for anonymous users.

Editing the custom block and saving does not invalidate the cache for those instances of the blocks. Looking in the "cache_render" table I see that caches for blocks get created through the Custom Blocks Library are set to never expire as a default with no options I can see available in the admin UI. 

I have to actually "Flush All Caches" using the Devel module to have the changes appear, or another way I have found is to go to the Block Layout page and click the "Save Blocks" button without changing anything.  The cahces for all the blocks will invalidate.

I don't want to give access to Devel to an average content manager or have to try to explain that they have to do a non-obvious extra step to have their block content changes appear.  Am I missing a setting in the UI that will invalidate the cache of those blocks on edit save?

I can cobble together a module that would add an extra submit handler that would invalidate the cache using \Drupal::service('cache_tags.invalidator')-&gt;invalidateTags() if I can get the cachetags for all instances of the block on save ... but I'm not sure how to get that info, and that just seems like a hack.

I'm hoping I'm just missing something.
I came across this question in the related questions sidebar on my question that seems to be the same issue with out-of-the-box core blocks:
Block cache not clearing on save?

The accepted answer from @4k4 on that question seems to confirm the issue, but doesn't hook in to the block save to invalidate the cache like I was thinking, but mentions, as one possible workaround, adding this to the theme:

function mytheme_preprocess_block(&amp;$variables) {
  if ($variables['base_plugin_id'] == 'block_content') {
  $renderer = \Drupal::service('renderer');
  $renderer-&gt;addCacheableDependency($variables, $variables['content'}['#block_content']);
  }
}


I don't know if this is the best answer, but it's simple and straightforward and seems to work at the moment, though it's a wonder that this would need to be done at all.  It's probably less of a hack than what I was thinking.