My pie chart for card counts in the stats section shows 0 new cards for a deck, yet I discover that there are still 6 more new cards in that deck.
The screenshot is from Mac release 2.1.49. I have also tested Anki Mac beta 2.1.50 (db804d95) and AnkiMobile 2.0.83 (20083.1) with the same issue.
I think it may be relevant that all of these new cards have siblings that are currently learning cards.
Indeed, as you have pointed out, it is relevant that these cards have siblings which you are currently learning, since this probably means that these new cards are burried, and thus are counted in an other category than new cards.
That does make sense. I had never noticed before, so I thought it must be a new bug. But in fact, I probably hadn’t noticed before because I recently changed the setting to bury new sibling cards to work around a different issue, whereas before I was burying only review siblings.
In that case, I have a small suggestion of a lower priority, and that is to break up the “Separate suspended/buried cards” into a two separate checkboxes.
Unlike the other states, suspended and buried are additional states upon the others. For example, every buried card is also either a new, learning, relearning, young or mature card. The difference between buried and suspended is that buried is temporary and will leave the buried state without any action by the user on the following day, and suspended is permanent until direct action on the part of the user.
When I look at the pie chart, I am doing so to get an overall idea of the study progress on the whole deck. The buried cards are not relevant to me when I look at the chart for that purpose. For one thing, if I want to know how many cards are new, relearning, mature, etc., then counting some of those as buried does not give me the whole picture of which “real” states my cards are in. For the other, buried state is applied to cards only during study, either directly by the user or (more often in my case) automatically as a result of siblings. Therefore, the buried count is up only after studying has happened. That typically means I have now finished my study on that deck for the day, and the next time I go to a deck, that buried count ought to be reset.
Suspended is different, because it is effectively a different state. These cards are ones that are not in any of the other queues for one reason or another, and it makes sense that they should be counted separately when I want to know the overall state of my deck. I never will get to those until I unsuspend them. Users will have different reasons for suspending cards. For me, I do so for two reasons: 1) when I enter new cards that I am not yet ready to study yet (such as a single note with all the principle parts of the verb, and I suspend all the cards for that note with stems that will come up later in my study), or 2) when I enter cards which I never intend to study but are for the benefit of those who share the deck with me (such as easier versions of my cards for the sake of my children).
More than merely knowing stats, I might as well mention a more practical reason, which is in fact how I came to notice what I thought was a bug: as I look to get an overall idea of the study state of the deck, I am especially paying attention to the new cards, so that I have an idea of when I need to make time to add more new cards.
Now that I have started burying new sibling cards, it appears that I now have no way to know how many new cards still remain queued up for the following days. When the new cards showed 0 in the screenshot in the original post, I thought it was time to add more cards. That is why I was surprised to find that some were still new. I see that I can uncheck the buried/suspended checkbox to find that I still have new cards, but how many of those are suspended and not ready to be studied, and how many are buried, meaning I will have new cards tomorrow? I can’t really know that. Some of the buried count would include review cards, etc., so simple subtraction by comparing the chart with and without the checked box is not sufficient.
I have a hard time explaining. I hope I have made it reasonably clear why it could be beneficial to optionally see the chart with suspended cards but not buried cards. But as I said, this would not be a priority “fix” in any case. I can get around it by using browse with “deck:current is:new -is:suspended.” It is just a whole lot less convenient in AnkiMobile where I always do my study.
One hint: You should be able to click on the labels (“New” etc.) and automatically do the correct query in the browser. This only works on Desktop though.
In that case, I have a small suggestion of a lower priority, and that is to break up the “Separate suspended/buried cards” into a two separate checkboxes.
I got your explanation, and it makes a lot of sense.
I’ll put it on my to-do list 
