Navigation randomly skips HISM instances

After Unreal Engine Issues and Bug Tracker (UE-48309) was fixed, I still have trouble with HISM.

The navigation considered HISM instances fine in UE 4.16.3, but is completely broken for my project in UE 4.17.1.

A line of dynamically spawned instances looks like this in 4.16.3 (with console command “show Navigation” and dynamic navigation enabled):

204481-navigation_4_16_3.png

The same level in 4.17.1 looks like this:

204482-navigation_4_17_1.png

As you see, it randomly connects instances, even though all instances have the same BP class.
Is this a known bug? Do I need to wait for 4.18 to use dynamically created HISM again?

Edit: All instances have the same Z position, so the reason cannot be one instance being smaller/above ground/whatever. Also, the result stays the same if I adjust the Z value. HISM also has “can character step on it” set to false.

I deleted everything from my game project in order to provide a minimal project to reproduce the issue. See the attached zip file.
[minimal project][1]

If you open this project with UE 4.17.1, run the game, fly around a bit for top down view, and “show Navigation” in the console, it will show the following picture:

Also note that I keep getting “save failed” errors with this simple map in 4.17.1, maybe this is related.

Hi

I’m currently looking at your issue, and hopefully it will make it in 4.17.2, will let you know.

A fix was made and will be available for 4.17.2

This is great news, thank you very much.

I had to skip 4.17 due to Unreal Engine Issues and Bug Tracker (UE-48361)
I just tested using 4.18 preview 2 and navigation is still broken with HISM instances for my project. The above minimal project works fine, however, so I’m afraid I have no small project to reproduce. Is this still a known issue in 4.18? I somehow fear I’ll be stuck with 4.16 forever or required to use individual actors.
This screenshot is from 4.18 preview 2:

214808-navigation-4-18-preview2.png

Well technically, the bug was fixed ans submitted in 4.17.2, i’ll check to be sure i bring the change back for 4.18 and will let you know.

So i confirm it was bring back, but i checked in yesterday, so it will be available in the next preview of 4.18 i guess.

Thanks, the navigation is fixed for me in 4.18 preview 3!

However, HISM is still broken for me compared to 4.16.3 - please see bug report https://answers.unrealengine.com/questions/712662/multiboxtraceforobjects-sometimes-returns-the-same.html . I guess I just use HISM for too much stuff :-(. So far I failed to reproduce this in a small project, if you need this I will try this weekend.

Glad to hear your issue is fixed, however for the other one, yes i would need a good repro or ideally a test project to properly investigate what is happening.

Thanks!