"It's a bug" is a possible answer
A lot of folks use some kind of tool to help them in play or with character creation/management. And sometimes those throw out results the user doesn't expect or immediately understand.
It's possible the answer is that it's a bug in the tool. If so, answers should be able to demonstrate that (and comments are useful towards clarifying any needed info). It's not the stacks job to identify where the bug is (though if it's a known bug, that's useful for such an answer.), but perhaps helping what is correct and/or how to workaround it.
Another possible answer is that the user as forgotten or missed a rule or character option, which makes it standard fare for us (and it doesn't matter whether it's a digital tool, DM, or some guide or video that's given them conflicting or not understood information).
These questions haven't been a problem before
An example gallery from other tools (in no particular order):