Funnel fetches data from Twitter Ads API. This is not the same data that is found on Twitter Analytics. To see the data Funnel fetches from Twitter log on to ads.twitter.com.
Metric sums are not consistent across dimension levels
A common misunderstanding is that metric sums are unaffected by which dimension level (Campaign, Ad Group or Promoted Tweet) is selected at connect. Metric sums on Campaign and Ad Group level will be consistent with each other. Selecting Promoted Tweet dimension level however may lead to metric sums short of those on Campaign level. This is because the Promoted Tweet level only represents the Tweets under the Ads category in the Twitter Ads Manager. On Campaign and Ad Group level, data from all Ads categories are included (Tweets, Display creatives, In-stream videos and Other).
Segmented data is not consistent with non-segmented data
It can be confusing to see that segmented data will not be 100% consistent with non-segmented data. This is however expected behavior according to Twitter due to how they derive the information.