Following.  The form 511-EIC is currently active on the Oklahoma tax commission site under forms.  https://oklahoma.gov/tax/forms.html

https://oklahoma.gov/content/dam/ok/en/tax/documents/forms/individuals/current/511-EIC.pdf 

The diagnostic says that it is under development.  It has now been released on their site so if anyone from support is reading this, please update so we can get our OK tax returns done. Thank you!