[thredds] featureCollection - Variable name change

I seem to have a problem when using the
<featureCollection></featureCollection> option and NcML to rename a
variable, i.e. <variable name"ice_cover_proportion"
orgName="Ice_cover_proportion"></variable>.
 
Without any alteration of the variable the shape of the
Ice_cover_Proportion variable is as expected:
Dataset {
    Float32 Ice_cover_Proportion[time = 45292][lat = 576][lon = 1152];
    Float64 gaussw[lat = 576];
    String latLonCoordSys;
    String crs;
    Float64 time_offset[time = 45292];
    Float64 latitude[lat = 576];
    Float64 longitude[lon = 1152];
    Float64 time[time = 45292];
    Float64 time_run[time = 45292];
} icecon/Global_ice_cover_proportion_best.ncd;

However, if I declare NcML to change the name, whether this is
inside/outside of a <protoDataset></protoDataset> declaration the shape
is wrong:
Dataset {
    Float32 ice_cover_proportion[time = 124][lat = 576][lon = 1152];
    Float64 gaussw[lat = 576];
    String latLonCoordSys;
    String crs;
    Float64 time_offset[time = 45292];
    Float64 latitude[lat = 576];
    Float64 longitude[lon = 1152];
    Float64 time[time = 45292];
    Float64 time_run[time = 45292];
} icecon/Global_ice_cover_proportion_best.ncd;

I'm not a 100% sure, but believe the 124 count represents the number of
data files in the dataset.
 
Is this a known issue in TDS 4.2.7? Is there a work around?
 
Kind regards,
 
Glenn