I mean, use an if clause and then run your code:

if (elgg_get_viewtype() == 'mobile') {
    
    // code here
    
}

But show us what you tried so far, maybe I can figure out what's wrong with your  code.

I am using this plugin with elgg 1.12.4 and it was working fine untill I upgraded my elgg to 1.12.5, now the navigation dropdown is not visible on the topbar. Any help/suggestions?

@Rohit Gupta

The difference between 1.12.4 and .5 is a few bugfixes. I don't think any of these are the reason to your bug, and I can't reproduce the error myself. Maybe you changed something else too.