Thanks so much for pointing me in the right direction, @lgladdy, and my apologies for hijacking the thread, @hellmute; I thought for sure this was the same issue happening!
For anyone else reading this, an important point that got me confused earlier – ANY plugin that does this incorrectly (as mine all did) can break the site for ALL ACF blocks on the backend. That means if you have multiple plugins that are including ACF, then you’ll need to add a conditional for each of those or have the plugin author do that.
