On a regular world, slash commands can be run using animation controllers in behavior packs. This is not the case on a realm. Putting the same world on a realm causes the commands to no longer be run or the transition state to never be recognized.
Reproduction steps:
Enter the provided world with example BP and RP
Right-click the entity to see a few /say messages specified in the animation controller
Upload the same world to a Realm
Right-click the entity on a Realm, notice messages no longer appearing
The interaction event sets a component group with scale: 0.5 to show that the BP is still working correctly. If the entity is not there, summon it using /summon test:example_entity
Same issue on BDS 1.14.1.4.