[Therion] Missing information in Survex 3d model output

Converting some Survex format data into Therion I discovered that despite entering the data in Therion, the Survex 3d model output from Therion is lacking some of the information which enables some of the most useful visualisation features in the Survex 'Aven' viewer. If I select 'Colour by Date' or 'Colour by Error' in Aven then none of my data appears to be counted as being in loops or having dates associated with it. Is this a known bug? Footleg