Invalid Bundle structure. Your app may contain only one executable file

I have seen this question before. The answer is: do you really need the static library. In our case: Yes

We have created a game (Starling) around a Text-To-Speech. The ANE that we have created uses the static library from Acapela (acapela-group.com/acapela-for-ios/). Everything is working fine. But when we upload our IPA to iTunes Connect we get an error about the executable file.

How can we solve this?