dpi
In the meantime you can construct your own views using documentation: [ Building views ](https://www.drupal.org/docs/8/modules/rng/building-views
I'd love to address this feature, but cannot justify the development time for the foreseeable future. Please register your interest in this issue by subscribing and/or +1 the original comment....
Under consideration for 1.4
Related: http://drupal.stackexchange.com/questions/230456/drupal-rng-trouble-with-maximum-registrants/230953
Changing to 1.5, 1.4 will be a quick fix release
Registration type can be multi valued or zero, so use checkboxes. 😒
Can sort-of workaround this by checking if deleted entities are not bundle entities. This still means that entities with non numeric ID's are still unsupported.
> Do you have hopes of integrating with CRM Core? I dont have any feelings either way since I have not used CRM Core. I am certainly not against integrating...