On the interface side, as soon as you add a custom activity entity to the lookup, the functionality stops working correctly.
In this case, it shows data only for this (custom activity) entity - not for any others:
In this example Medication entity - my custom activity entity:
It is contained in the list of entities that should be displayed by lookup, but it turns out that only the one is displayed.
As soon as we remove the relationship with this entity, the lookup starts working as it should:
This case was verified by creating appropriate relationships in both XRM Poly Lookup Creator and using C#-code.
By the way, next case - bulk edit - also doesn't work correctly:
Or maybe you know how to avoid this? What does this error say? What should I do?
P.S. There is also a bonus with data import, but you can check it yourself. If it is interesting, I will tell you a little bit later
It is clear that it is difficult to expect much from the preview version, but it is necessary to understand the pitfalls. Be careful!
By the way, I tried to create another custom entity (not activity) and connect it to a multi-lookup - a similar situation. Multi-lookup works only with my custom entity, and the rest are not visible on the interface.