The State of Colorado has been experiencing communication problems with the IRS system since 8/29/18 (state returns get processed through the “IRS system”), which results in the CO state returns not having a rejected/accepted status.
The state has requested tax preparers (and tax payers) to not contact the state of Colorado if you have concerns regarding the status of a state return. Colorado is working on correcting the issue and you will receive a notification once the return is able to be processed.