Blueprint Breakpoints are changing runtime behavior of Nodes

Here’s footage and a quick run through of the bugs I was facing in my relatively small game.

There were two main bugs I faced (See video above for demonstration and code details):

  1. Breakpoints were not firing on a node that called a function, but they were firing inside of that function (I confirmed that the function wasn’t being called from anywhere else) meaning it passed over nodes with breakpoints without them firing. I have learned that this is a known issue with Breakpoints in AnimBPs in UE5.0+

  2. Having a breakpoint in my blueprint altered the way that the nodes behaved (This is demonstrated at 1:55 in the video) . A node that should be providing a movement impulse on a character wasn’t properly doing so (still trying to debug the cause of this), but when I placed a breakpoint on the node, it began working? Upon taking the breakpoint off, it stopped providing the movement impulse. No other changes were made, and I confirmed (off-video) that the node is correctly being called by replacing it with a simple print node.

Happy to provide any other code or details. Thanks!

Just for the record, I’m having a similar result. I am slicing procedural meshes and keeping track of the slices so that I can spawn a new actor with the same parts history of slicing.
When I disable physics on the procedural mesh or add breakpoints to the Slice nodes, everything works.
When I enable physics and don’t hit any breakpoints, the child actors seem to ‘forget’ previous slices or fail to spawn.
I’m thinking there must be some sort of race condition and hitting the breakpoint allows a variable to resolve somewhere, but I can’t figure out where.
So you’re not alone OP, although it doesn’t seem like this post is getting much attention.

Came here because I’m experiencing similar issues to your second bug.

The first however, in the video it looks likes you’re debugging the Preview Instance of your animation blueprint in the EventGraph whereas in your function it is set to No debug Object Select which probably defaults to the Game Instance of your selected object. That or since it’s a function the breakpoint will trigger on all instances of the ABP.

Beside that play button you have a dropdown which is used to select which instance of the Animation Blueprint you want to debug.