# Problems with Simulate (Alt+S) play test - Blueprint/variables getting erased - How do I fix this?

**URL:** <https://forums.unrealengine.com/t/problems-with-simulate-alt-s-play-test-blueprint-variables-getting-erased-how-do-i-fix-this/1821894>\
**Category:** Programming & Scripting\
**Tags:** simulate, unreal-engine, simulation, Blueprint, question\
**Created:** [April 26, 2024, 12:07am UTC](https://forums.unrealengine.com/t/problems-with-simulate-alt-s-play-test-blueprint-variables-getting-erased-how-do-i-fix-this/1821894 "2024-04-26T00:07:29Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![SergioAAV](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@SergioAAV](https://forums.unrealengine.com/u/SergioAAV)\
**Post date:** [April 26, 2024, 12:07am UTC](https://forums.unrealengine.com/t/problems-with-simulate-alt-s-play-test-blueprint-variables-getting-erased-how-do-i-fix-this/1821894/1 "2024-04-26T00:07:29Z")

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Hello everyone!

I have a Skeletal Mesh with a Control Rig and an Anim Blueprint.  
I exposed some variables from the Control Rig to the Anim Blueprint so I can control some positions by value.  
Then, I created an Actor Blueprint that has my Skeletal Mesh with the Anim Blueprint set. In this Actor Blueprint, on BeginPlay I’m getting a reference to the Anim Blueprint being executed using GetAnimInstance, casting it to my Anim Blueprint class and saving the reference in a variable. Then, I created some Instanced Editable variables and in the Tick Event (just for testing) I’m setting the previous exposed variables from the Control Rig → Anim Blueprint.

If I use the normal Play, everything works. If I change the value of the variables in my Actor Blueprint, my Skeletal Mesh moves accordingly since those nodes on Tick get updated.

The problem starts when I tried to test things using the Simulate play (Alt + S). If I press Simulate and do the same thing (change the value of the variables to check the movement) nothing works. I attached some print nodes to each step to check if the reference was getting caught and values were being passed correctly, and what I noticed is that after pressing Simulate, everything is assigned correctly, but if I change any value manually, it seems the blueprint stops being simulated and all the values are erased.

Is that the normal behavior of Simulate and I never noticed before because I never tried to twitch things while using it, or did I do something wrong? If that is the normal behavior of the Simulate play, is there a way to change it so that the blueprint keeps executing if I change a value during execution?

Thanks in advance!