@eugene150 You’re right - it looks like the size of the collider for the bomb and the collider for the explosion effect are just the right size so they overlap when diagonal like that. I adjusted the size of the bomb collider, which seems to work.
Make sure you select the prefab for the bomb, and select the collider sub object. I changed the x, y, and z scales of the collider to 0.12, which seems to fix this issue.
Hope that helps.