Hang and memory spike (that doesn't go away) when you create an endless loop in AnimBP. Blueprints have a safeguard against this when you try to PIE with an endless loop, but I think the Animation Preview doesn't have this same safeguard.
1.  Create a ThirdPerson Template project
2.  Open the ThirdPerson_AnimBP
3.  Set up the EventGraph like in the attached screenshot (Add a print string and make it loop with Set Speed
4.  Compile the AnimBP
Result:  Long hang and memory spike
Expected:  A warning about the loop
Infinite loop was created, not an Engine bug
Head over to the existing Questions & Answers thread and let us know what's up.
| 0 | 
| Component | OLD - Anim | 
|---|---|
| Affects Versions | 4.9.2, 4.10 | 
| Created | Oct 27, 2015 | 
|---|---|
| Resolved | Oct 31, 2015 | 
| Updated | Jul 14, 2021 |