In that case, I think it was me who submitted the report to IRCC because in my WES account, it is mentioned that the ECA report of my Bachelors is also sent to IRCC apart from me. Yes, I completed this MBA while I was working full time.When you apply to University, you don't need to disclose you already have an MBA, that's up to you. You'll need to meet certain admission requirements for sure and that's what you need to have proven. That is not a problem.
Regarding your ECA, I don't think IRCC receives any notification from the institution performing this. It's wouldn't make any sense for them to be receiving this information, with what purpose? I am not sure about this but I highly doubt there is any connection. You will receive a report however that you can submit to IRCC,but most certainly IRCC will not check on each study visa applicant whether they've had any credentials assessed or not, because that's not something you need to get a study permit.
First you should worry about getting admission into a program, and then worry how you'll go about when the time to apply for the visa comes, if it comes at all.
Since you have said you completed this MBA online, I'm guessing you did it while working so I am sure you will be able to account for this time in some other way. So you should probably not worry about including this information in your visa application. What you need to do is convince the person assessing your application is why you want to go back to school after such a long time, that's the important thing.