Hi. I initially reviewed this post and thought it was correct, but this use case is specifically asking about Relevance strategies. There is a different category value for relevance strategies. Please try:
1. In the strategy, click on History tab to add a custom field.
One thing to check is that the relevance strategy is saved with the correct applies-to class. Only strategies of the correct applies to class will be displayed.
BTW, is this for a new implementation? If so, I recommend you start with a newer version of NBA Designer. These relevance strategies are actually no longer needed with the new NBA Designer approach and we highly encourage all clients to move to the new approach.