Inserting Column Not Working - for Pro User and Admin

I'm just became a paid Pro user (separate individual monthly account).

A co-worker has an account and created several sheets which have been used for years.

A new sheet was created, and they made me an Admin for the sheet.

When I click dots in column header, and select Insert Column Left, I can enter a column name, and column type. However, when I click Ok, nothing happens, it just stis there.

I noticed also the Insert column button in header is grayed out.

I did close all windows & tabs with smartsheet, and also logged out. Then opened a new window, and logged in, and still cannot insert a column.

If you can help, it would be appreciated, thanks