.txt in nuget will be content but do not copy when downloading, I want it to be copy always

I have a project which I create a nuget from. In that project I have a .txt file set as content and copy always.

when I then in an other solution install that nuget in a class library (visual studio c#), the .txt shows up in the project but is set to content and do not copy.

how can I get the default value to be copy always?

(my goal is to be able to just run that solution and get everything in it in the bin folder)

I have tried in my .nuspec to add:

<contentFiles><files include="*.txt" buildAction="Content" copyToOutput="true" flatten="true"/></contentFiles>

it doesn't seem to work