Movement system in BP refuses to work after ~1,5s of gameplay

i have the craziest problem in my game.

The blueprint in screenshots is a simplified version of my playerBP made just to test this problem.

It is a destructible mesh with physics enabled and gravity disabled. It moves using a Physisc thruster.

The pawn have 5 speeds: 0 is a reverse gear, 1 is stop and 2,3,4 and forward gears. So for example when i push W, it changes the gear up and it also change the multiplier for the thrust strength for Physisc thruster as shown in the attached screenshot and the mesh is moving forward.

Everything works fine when i hit W or S in the first 1,5s of game. After ~1,5s it stops to work. Everything in Bp is ok. Gears and multiplier are changing but mesh is not moving and it stays that way no matter what i do.

In my original playerBp i noticed that in the same moment that this happens the mesh also change its mass to 0. I dont know why.( in the testBp this is not happening).

There is one more thing. In 4.18 when i was looking for a soultion i noticed something funny. When i have 3d viewport as main window, mesh refuse to move after ~1,5s, but when i move the blueprint window to my second monitor so i can see both 3d viewport and BP everything works fine! In 4.19 it’s ~1,5s in the first case and ~6,5s in the second.


EDIT: Recreated and tested it in a milion ways again in 4.20 and the problem still occur, so im adding a BUG tag.
Also, everything is working fine if i attach the thruster to static mesh instead of destructible and make it a parent, so propably the problem lies in the destructible component.

Is the aplly Damage On Impulse checkbox ticked?


There is one more thing with destructible. When i add destructible as an actor component and set the destructible mesh there, when i hit Play the destructible mesh is not there. It is not spawning! I have to manually set it again using “Set destructible mesh” after “Event begin play”.

So I thought maybe there is the problem. And i was right.
Now the “Set destructible mesh” node fires when im changing speed of my pawn and now everything works fine. I can move my pawn everytime. I just don’t get it…

I assume you mean “apply impulse on damage”. It is. But switching it on and off changes nothing.

This is my current workaround. It fires with every speed change.

Destructible mesh ZEW is root component of the actor. It works fine for flying around, but i guess there will be problems when the mesh will be damaged…

Ok. i thing i have found a solution. I believe that the problem was with the destrictible falling asleep after this ~1,5s. I changed it’s sleep family to custom and then changed Custom Sleep Threshold Multiplier to 0. After a few test everything is looking good but i need to test more.