Why don't you just do 'ctrl m', then choose an axis to mirror the objects along the x axis instead of doing all that weird view port stuff?
I should use CTRL + M more. Honestly it's one of the bazillion Blender hotkeys I don't remember 😅
One thing to keep in mind about CTRL + M is that it still inverts the normals. So it's not a "clean" mirroring function.
Ahh, ok. I'll remember that.
