Converting to static mesh with mirrored objects

When designing some of the buildings with my team for our game, I did not anticipate that mirroring objects along the x-axis would pose a problem in the future. Despite this, I continued with my processes. However, when I attempted to convert all my work into one static mesh, the mirrored objects appeared black and invisible. Initially unaware that the issue stemmed from the mirrored objects, I attempted to resolve it by restarting Unreal Engine, but to no avail. Converting the object into an actor and then into a static mesh also failed to rectify the problem. Eventually, I discovered that merging all the objects instead of directly converting them to a static mesh provided the solution.