What is the exact version you are using? There was also a bug fixed with similar error. Then, I would check the page template you are using - maybe you have re-used some of the sample templates and it may have had MVT setup. Please check the OM_MVTCombination table and clear it out if there is any data there.
Another option is to check the pages what template they are using, after you find out what template is used you could do the following:
Delele all the problematic tasks from the list in Staging application.
Delete given page template(s).
Create new page template(s) and assign it to these pages.
This would ensure there is no reference to some MVT testing. You can try it with one particular page to be sure it works and then perform this for all problematic pages.