I have tried over and over again to set up an action to Merge Visible and Save As. The merge visible works. The save as works, except it does not change the name of the file on the tab. Therefore, the next save command does not show the latest filename. Using Photoshop version 22.4.1 on Windows 10 PC.
I was wrong from the Bridge I see your issue. The same test from Photoshop there is no issue. I also do not get the .NEF in the tab. You should report the Bug to Adobe on the site for reporting Photoshop bugs https://feedback.photoshop.com/