Bruno reported during the VStar May 2014 course:
"When I load data from the AAVSO database and add data from an ASAS file, I don't have the possibility to filter on "Observer Code". It disappeared from the pattern search box. But View > Filter still works!"
I have verified this unintended behaviour. The information is still there, as can be seen by the observation details dialog. However, some keys (observer code, charts, ...) in that dialog show as null. This brings us back to https://sourceforge.net/p/vstar/bugs-and-features/409/ which I suspect is happening because weak key references to observation attributes in ValidObservation are being garbage collected, presumably due to a map being cleared.
What really should happen is that the observation attribute maps need to be merged or the previously loaded observations' attributes otherwise retained.