So I run into this problem if I want to convert a NIX file to a neo object that the Neo implementation expects an offset in the sampled_dimension for the package quantity to function properly.
This breaks even if you set the offset = 0 in the DataArray.append_sampled_dimension method. It does not add an offset because of this check
if offset:
smpldim.offset = offset
my solution for this problem is simply set the default offset value from None to 0 and remove the check.