In your screenshot, the formula “Estimated Time” token has “T” next to it, indicating that it’s a text field – it should have a clock icon next to it. Even though I can also look at the column in your screenshot and see that it appears to be set as a time column.
My hunch is this is buggy behavior, where the column has not registered the proper column type. Try “jiggling” this until you get past the bug. Create the column anew and try hard-coding a time value into it, then delete that value, then add in the formula. (This exact sequence as worked for me with this exact buggy behavior.)