The dropbox link isn't working for me so I can't look at the family for you. But here's some generic tips for solving this kind of problem.
- If you are reading the Host and HostFace properties within the same transaction that the instance was created in, try doing a Document.Regenerate() before accessing the properties.
- Try reading the properties from a seperate API command (place using one command, read using another).
- When you select the API created instance in the UI, see if there is a property that references the host element. Now place another instance of the same family using the UI, is the property of this one the same?
- Read the host parameters of a UI placed instance using the API. Do they appear now?
- Try different overloads of the NewFamilyInstance method.
- Check the value of FamilySymbol.Family.PlacementType this will give you some insight into which overloads can be used and which parameters will be available once the instance is placed.
- I've found than many ceiling related families such as lights and fire sprinkler heads are created using family templates that do not store the reference that you selected for placement, they instead store the location, level and height above level or offset.
- Create test families using a few different templates, place them using both the API (using differring overloads of NewFamilyInstance) and the UI then read out as much placement info as you can for each, this will give you an idea of the different ways family instanes store thier location / host information depending on the family template and creation method.
Hopefully one of these helps you out, otherwise, update with a new link to the family an I'll check it out for you.
