how to reproduce:
1. create two nodes: (A) text with bold,italic and strike-through and (B) without any formatting.
2. copy the format of A (format, copy format), paste into B (format, paste format).
You can see that bold and italic did copy from A to B, but strike-through did not. This it the bug.
By the way, it does apply in the opposite way. If you copy the style of B and paste it into A, the strike-through is being removed on A also. So in this case there is no bug.
Please don't change the functionality of copy and paste format, its an amazing tool - just this tiny bug.
Diff:
Preview 1.9.14_01