This question can be asked to almost all features of wpDiscuz addons. The answer is simple, we have to monetize this project to be able to keep it improving and developing.

Currently, you can see more than one hundred of features in the free core plugin and tons of settings to make it easy manageable, even the designs and layouts are not one, we added all three in the free core plugin. All new cool features like Inline Comments and Live Notification Bubble are also in the free plugin. This says our projects are not payment oriented, but they must have some paid extension for financial support.

Most of the paid features are the features which are in the scope of custom areas, the file attachment feature for custom content type is a good example. You can see that all features of wpDiscuz are not limited for custom content types and custom roles. The only limited feature is the image attachment to have a good reason buying wpDiscuz Media Uploader addon. This addon has many good features as well:

1. It allows managing and uploading any type of files you want, not only images.

2. It allows to attache multiple files, not only one.

3. It brings lots of settings in wpDiscuz > Settings > Content & Media Tab to manage attachments.

4. It adds filter button next to the and buttons.

And lots of other cool features. So buying a paid addon you're donating wpDiscuz project free  development and the free support, and you can be sure this project has some income, and it'll not be abandoned one day. The monetized project are more reliable and trustworthy.

As it's already mentioned here the default "Attach an image" button is only available for the post, pages, and attachments post types, and for default WordPress user roles. For custom post types and custom user roles, the button is not accessible. For more advanced features, we recommend to check out the wpDiscuz Media Uploader add-on.

Some users say they cannot see the attachment icon, but have previously. I tested myself with regular users and I can see it. Is there any particular reason why some users suddenly cannot see it? I have made no changes in settings.