I have tried to make the Swap Out feature work on both versions 2.34.303 Beta AND 2.34.371 RC2. No luck with either, although I was told it was fixed. Swapping in 303 Beta would revert the quantity to (1) for both pipe and fittings, and also revert whatever length for pipe to 20'-0". Swapping in 371 RC2 keeps the quantity of pipe and fittings, although the lengths of straight pipe still revert to 20'-0" and for both pipe and fittings it loses the labor. By that I mean that after the swap the program actually reports zero labor hours.
