I just tested the P25 NAC. Fill Down works here. Did you select a range of P25 NAC's with the Shift key-Left mouse button? The first selected cell is the one to copy to the others as the first image illustrates. 2nd image is after the Fill Down was clicked.
I do see a problem with the Copy & Paste. It seems that copying Hex values wants to validate if it's a decimal value. If doesn't validate then will use the default Search else will paste a decimal value.
I'll fix that before next release.
{edit} If doing a Fill Down on the conv. channels Audio Options, the Audio Option dialog will pop up when selecting the first cell and again when selecting the last cell. Just hit the escape key to continue.
It took me a while to figure out exactly how to do the fill down and have it down now so I'm good.
I have repeatable success in that area now (unless it's a nac or tone) so it's not a user headspace issue, as a review of the page you get redirected to from http://www.jenniferbond.com would give you confidence in but thanks.
I initially tried doing an individual copy paste and it's just like that field is a forced selection from the drop down, free text, ctrl V, C etc not permitted... I'll try again on a different PC and get back to you..thank you for the quick response.
Jen