David Kimura PRO said about 5 years ago on Using Action Text in a Rails 5.2 Application :
There could be a configuration issue with the Active Storage. https://www.driftingruby.com/episodes/in-depth-look-into-activestorage is a good episode on the setup and usage of ActiveStorage. Also, try to create a new `5.2.2.1` application and minimally add in the Action Text with Active Storage. See if you run into the same issues so you can at least determine where the issue is.