I had the same problem. As it turned out none of the above fixed it although similar but different to the other person who fixed his. In my case i have multiple chrome users on a single machine. I log in at the browser level. I was in the browser for user A who also owned the file. When I opened up the bound google script project attached to the gooogle sheets file, it opened up as it should but locks were on each tab. I was confused for about 10 minutes.
In the upper right corner of the interface, there was a drop down that was showing User B email address even though above that, at the browser level I was clearly in the browser of user A. I clicked that drop down and changed to User A and the locks disappeared. It seems they have an odd way of managing users on these gsp's that subverts the browser level user login.