Hi,
The "Polling" status means your submission was successfully sent to HMRC and we are waiting for their confirmation. Normally this takes just a few minutes, however HMRC is currently experiencing delays in processing CT600 submissions, which is why yours has been in this state since yesterday.
This is entirely on HMRC's side — your submission has been received by them and is sitting in their processing queue. There is nothing wrong with your filing and no action is needed from you at this point.
Our system will continue to automatically check with HMRC for a response, and your filing status will update as soon as HMRC processes it. You can also visit your filing page on WeFile at any time to trigger a fresh check.
We apologise for the inconvenience and appreciate your patience.