Hello @udapud,
Glad you like the plugin and sorry to see you are encountering such issues.
The plugin does not have any conflict issues with WordPress menus on a vanilla install, so it might be a conflict with something else.
Since you have ubermenu, most probably that is the source of conflict (something from our end or from their end is not working well together). Ubermenu is not a free plugin so we cannot install it ourselves to try and replicate your issue, so we have to work with logs.
Would it be possible to enable debug on your WordPress website, reproduce the issue and send us the logs?
If it is a busy live website do not leave debug running once you reproduce the issue.
Looking forward to solving this issue.