Since the October release of Analytics (October 2019) we have the option to filter out Unspecified/None in Analysis Workspace. This feature is great for eVars, since we can conveniently filter out those values.
But this filter has a massive flaw in it's design. Not only does it affect eVars, but props as well. The problem is that there is no Unspecified/None for props! This concept has always only been applicable to eVars.
This has two effects: The first one is only annoying, since we now have Unspecified values in tables for prop-dimensions that we need to exclude. The second is much worse, because it changes how time spent metrics work and breaks them in the interface.
To compare, pull up a freeform table with your most popular pages, using the page dimension and Time Spent per Visit as a metric. Now, activate and deactivate the Unspecified/None filter. The time changes! This does not happen with eVars, since Unspecified is a "real value" for them but not for props. If Unspecified is included, the time spent is much lower! The worst part: If you trend time spent metrics for props, you can't exclude Unspecified at all, so you are stuck with the much to low values. In the old Reports and Analytics interface, you can still get the correct values (if you have a lot of time on your hands). If you want to know why this happens, I also blogged about it.
This is something I already brought to Adobe's attention, but to no real effect yet. They don't see this as much of an issue. But I do! We need correct data! And since time spent is a major KPI for media companies like mine, this critically affects our business.