Hi Arkyadeep,
In your case, I can understand that your enfolding all 3 layered modules in a single application.
kindly check your Enduser module naming convention once, if it falls under any of the foundation module namings. This issue may arise due to that.
Also look at these posts it can help,
https://www.outsystems.com/forums/discussion/59771/cheat-sheet-outsystems-module-naming-convention/
https://success.outsystems.com/Documentation/11/Managing_the_Applications_Lifecycle/Manage_technical_debt/Code_Patterns
Regards,
Saravanan Santhanam.