@ashikai – Can you confirm everything is on the latest version? If so can you also confirm your using one of the default themes? If not I’d say your theme is likely the cause as I just fired up a fresh install of WP 5.4 + WooCommerce 4.0.1 + User Menus 1.2.3 and its working correctly for me:
Keep me posted. But from everything I’m reading in the support forums for other plugins that also add nav menu fields, there are a lot of themes and less popular plugins that did not update for WordPress 5.4 core updates and that is likely what is happening in each of your cases unfortunately.
Maybe i’m wrong, but so far all cases that I have personally dealt with which have been resolved or at least debugged fully were from an out of date theme (hasn’t been a plugin so far for any of our users though).