In my humble opinion, and this is just a personal suggestion and not a criticism of how you manage your community:
Tag enforcement is a useful feature when there is an abundance of content and users need to filter out the relevant information from the noise. However, it can also discourage some people from contributing if they feel pressured or annoyed by the tag requirements.
Finding the sidebar on some mobile apps can be challenging for some apps making it difficult to even get the list of acceptable tags adding tags to their posts.
I would recommend that you encourage and recommend tags, but refrain from pestering or threatening to delete posts that do not have them, unless it becomes a serious problem for the community.