I've successfully been using the registry setting described in http://docs.wholetomato.com?W332 for about a year. 1810 and the previous version both seem to not completely work when using it though. One of the noticeable problems is often 'Goto Implementation' will not work with locals when using an alt directory path (which happens to be on a ram disk).
Finally figured this out when getting more information.
The drive was full when VA was showing unusual behavior. Parsing seems to be retried occasionally, continually failing I guess, but nothing can be written out. When it doesn't have the data it just doesn't do certain things - basically the same behavior as if it hadn't fully parsed everything yet for a file you are viewing.
Thank you for the update. I don't think anyone else has ever run out of space before, but I can see how this would cause this problem. As you say, without any space VA cannot add new information to its symbol database.