I created a custom data model and put in a few document types. Within those, I have several text fields/properties that are set to "Free Text" as the indexing option. However, when I put content in, change the type and then fill out those properties, no matter how long I wait, I cannot search on the values I enter.
Searching on prefix:field:value works fine, but the average user will not typically use this.
Based on online information related to this, I believe this is functioning as designed but leaves room for improvement. In my opinion, the ideal scenario would be that anything you can do in the UI (such as via Model Manager) should be applied across the whole platform (such as search settings) for the sake of consistency.
Custom properties marked as searchable should automatically be added to the search index and appear in Full, Live, and Simple Search results when searching on those values.