Weird issues that only happens on iOS but not Windows

This is my 2nd encounter of weird issues that is out of my control. Blueprint scripts work fine on Windows but not on iOS devices.

My first bug was having event ticks not firing off when a blueprint actor class has a variable of its own class.

My recent bug was having some nodes (Visiblity & Transition) in blueprint not firing off although the print result shows otherwise.

All these issues only appear on iOS devices and not Windows. Worst of all, it does not produce any crash log on my device. Is it a possible blueprint corruption? I tried debugging with session frontend but everything came out green.
I was wondering if anyone experienced similar issues and what are your resolutions?

TLDR: Anyone encounter issues where blueprint scripts break on mobile devices (specifically iOS) but work fine on Windows? What are your solutions?

Did you try building a stand alone Win32 executable? I remember stumbling once or twice upon issues which would only show up in deployments, not in the editor.

But I already know about your first problem: An actor having variables of its own type didn’t work properly for me, I would lose references when recompiling and on deployment. I got around that by parenting the actor class to a “base” class I created, and using that as the variable type (performing casts whenever I wanted to use it).

Yeah this won’t be much help to you but I had this happen before where it wouldn’t work on iOS but would in the mobile preview. In my case I even hooked up a print to screen at the end of what was supposed to fire off and print worked but not the other thing. I got no response on my question of the answerhub but I just ended up rearranging the blueprints a different way to get it to work.

Thanks for the replies! Those are some interesting solutions that I am going to try.

I actually did try a stand alone executable on Windows and it worked, it only broke on mobile devices sadly. The weirdest thing is that it worked previously and broke out of nowhere (did not touch the blueprint script in a while).

It’s all good, I just wanted to start a discussion on this weird issue and see if any of us has a solution or come up with a solution together. What you mentioned is exactly what happened to me, things will just print out as if the blueprint script went through all nodes perfectly but some nodes in between just don’t run. Lost a few hair when this happened.


I did some more test today and found out that this only happens on child blueprints where it inherits a base class with logic in it (in my case). It never affects the base class (spawning the base class works perfectly). Unfortunately, recreating the child class doesn’t resolve the issue, and I can’t reproduce this as it happens randomly. This issue is scary when you have a lot of child blueprints that inherits a base class. Right now my last resort is to recreate the base and all the child classes from scratch to make it work.

*There is a reference number: UE-18866. I have no idea how to view it though, but lets hope it will get fixed soon.

If the suggestions provided above do not fix the issue you’re running in to, please post a question to AnswerHub description the exact reproduction steps so we can get this bugged, if it happens to be a bug.