Flosum uses the “last modified date” of a component to detect when the component was changed. Depending on this field (“last modified date”), the component is pulled into the snapshot based on the value specified by the user in “Number of days changed”.
However, the last_modified_date of a standard component never changes. For other components such as custom fields, the last_modified_date changes if the description or the field type is changed, but not if the picklist values are changed.
And, then there are metadata types that do not expose a “last modified date” via the metadata or the tooling API.
These component types cannot be retrieved during snapshot creation based on the “Retrieve changes in last X days” field on snapshot create screen.
The list of these metadata types is:
1) CustomField(standard fields e.g. Account.type or Account.phone that do not end with a "__c")
2) CustomObject(standard objects e.g. changes made to standard components of standard objects like Account, Case, Opportunity etc)