Plan estimate values are totaled in the milestone scheduled item view ONLY if the user story is also associated to that milestone.
The Milestone scheduled item view total for plan estimate in the first screen is calculated based on the feature as well as user story relationships to that milestone. In this example F2 is associated to milestone M19 and therefore F2 is shown in this view, but by definition a feature does not itself have a plan estimate so no value shown or attributed to F2 for plan estimate. It is the artifacts themselves that are contributing to the total here. Note that US46 shows up twice, this is because it is part of F2 (which is associated to milestone M19) AND US46 is also associated to M19. US46 shows up as a child of F2 and as a separate line item as well. However, by design US46 (10 points) is only counted once in the total for the milestone. US50 is shown here because it is a child of F2 but US50 is NOT explicitly associated to milestone M19 so it's 10 points are not part of the M19 (milestone scheduled item) total. The 13 points total plan estimate for M19 are coming from DE16 (3 points) and US46 (10 points) as both of these artifacts are explicitly associated to milestone MS19.
The Portfolio collection view in the second screen shot is calculating the plan estimate total based on the fact that the user stories are direct children of F2. Each user story has a plan estimate of 10 for a total of 20 points for F2. The Portfolio collection view calculation has no relationship to the milestone view calculation and the two totals may be different in some cases.
The calculated totals are taken from the perspective of the page or view (milestone vs. portfolio item).