Bizarre thing happened today. I went in to look at a T4 which I submitted Jan 11th. The CRA shows that they have received it but all transmission details in TaxCycle are gone. I submitted prior to the dental update (I believe) so not sure if that is a problem. When I select Transmit (which is the easiest way to see the date of submission) it states there is an error (dental detail missing) and does not show it as transmitted. This caused some heart failure until I went to RepClient to ensure that it was received by the CRA.
It wouldn’t explain what happened, but if you have that T4 client loaded in TaxCycle you can select File then History which will give you quite a bit of information, including the actual transmission.