Hi @odizeuz,
Happy to look into your issue with Custom Activities on the windows SDK. Please fill out https://goo.gl/forms/xIWnym9wwdZhiEYw1 so we have an idea of your setup and can provide better support moving forward.
For this particular setup, can you please share how you are calling the Custom Activity? The exception is saying it cannot find the activity. Do you have that package installed on the device?
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