I have a simple AI character and a few different levels that use the AI character .
This work fine when loaded individually , the problem is that whenever they are load as a sub level it will say the “Navigation needs to be re built”.
Re building the navigation makes no difference .
I am using engine version 4.5 and under Project Settings / Navigation system all of the options are set to true .
Are there any other settings that I need to change ? Or another way around the problem?
Thanks
Just a random thought but is your nav volume large enough? Navigation will only be built within that.
The navigation volume is large enough , it just only appears to work on the persistent level .
Do you have to have one navigation mesh for the entire level ?
No you can have as many as you want. Though I’m not entirely sure how they work if loaded dynamically. That was a very easy and small thing which happens quite often when starting with the nav mesh… I didn’t do a lot of work there so I’m not sure of a lot of breakpoints and what to care about. Sorry :S
Found the issue . There is a begin play event in the AI blueprint that was not being called in the sub level . I added an extra event in level blueprint and it is working .
Thanks for your help .
No worries. I happy you got it working! 
Could you add this here as answer and accept that so other people know it’s solved?
Thanks!