@Pellaaa93 To ‘save’ generated assets, please use the Merge Actors feature. It’s recommended to save your work & make the assets much more performance friendly. You can see an example of merged assets in the demo map with merging examples.
A ‘reset’ like you described should not happen anyway, maybe something interfered with your scene setup. You can try changing one of the parameters inside of the problematic assets and see if it helps. It should regenerate the asset. You can also try moving the asset a little bit, so it has a chance to re-generate.