Symptoms
I am trying out the K2 Mobile app for Windows Phone and I can login and see my tasks, but if I try to open a form, I get 'Failed to load the form - Internal server error - 500 Internal Server error'.
If I open K2 Mobile on my iPad, or open in browser, it works fine when opening the form for the same task.
Diagnoses
Known issue specific to windows phone.
TFS 516106 - K2SF Runtime MobileRuntime WindowsPhone: When accesssing the designer from the in app browser, active x controls are not supported which causes Smartforms not to render
Resolution
Fixed in 4.6.10.