I ran a couple of tests on our end. I was unable to reproduce the warning that you are seeing on your end. Could you provide a detailed list of steps (including any small steps that may have been over looked) to reproduce this issue on our end?
I will see what i can do, to provide a more detailed breakdown of the steps.
For the above log, i simply created a new project using the VR template in 4.15, packaging for development and using inclusive method of nativizing blueprint assets. I may also re-install 4.15 again , just to be sure.
I was able to reproduce this issue on our end. I have written up a report and I have submitted it to the developers for further consideration. I have also provided a link to the public tracker. Please feel free to use the link provided for future updates. Thank you for your time and information.